Though it could be argued that Germany was "posed" for war, they did not mobilize troops or invade France before the war began in 1914. Therefore, the "German Invasion of France" is an incorrect answer. 

Each of the other options contributed to the eruption of war. Feelings of intense nationalism spread across the Baltic states. Slav nationalism was encouraged by Russia, but it scared Austria. The Austrian empire felt threatened by the Baltic region, after the Balkan Wars (1912-1913), because of the large Slav populations in the South. This caused Austria to align with Germany and contributed to the escalation and cause of the first world war. The rapid militarization in Germany also contributed to the breakout of the first world war as it posed a threat for surrounding countries. This militarization was influenced by colonial/imperialism desires that ultimately caused a naval/arms race between Germany and Britain. There were immense internal political issues in Germany, including but not limited to: economic issues, decline of the Kaiser's regime, and rise of social movements. Ultimately, all of these contributed to the cause of World War I.

The Axis Powers refers the group of countries that were united together during World War II against the Allies. 

The correct answer includes the full list of the Axis Powers: Germany, Italy, Japan, Hungary, Romania, and Bulgaria. Some might say that Austria would not count as one because it was considered a part of the Axis Powers because it was annexed by Germany in 1938. The other options are only partially correct, thus the full list is necessary to get this question right. 

The Russian Revolution in 1917 had many complex causes, some were deeply-rooted in society at the time whereas others were more immediate. Succession of wars, the rise of the working class, mass disapproval of the Czar, and issues facing peasants all contributed to the outbreak of the revolution; however, Czarism ended because of this revolution and wasn't a cause. The other answers are all direct causes to the growing discontentment of the Russian people that prompted a revolution.

The Cuban Missile crisis was a 13-day confrontation or stalemate between the Soviet Union and the United States. This happened once Soviet missiles were found just 90 miles away from the US show. The Cuban Missile Crisis, also known as the October Crisis, was the closest point to escalating to full-scale nuclear war during the Cold War. It happened between October 14-28, 1962 during the Cold War. 

There were many results from the Second World War. Millions of lives were lost, but there were also immense political consequences. Europe was essentially divided across Germany (East versus West), and it was the "iron curtain." The East was under the influence of the Soviet Union whereas the West was influenced by the Allies. This created tension throughout the Cold War and enhanced other consequences from WWII especially for Germany.

The correct answer for this question is the "Creation of the League of Nations." The United Nations was created after the Second World War, whereas the League of Nations was a result of the First World War. 

The correct answer is "the assassination of Archduke Franz Ferdinand." The assassination of Archduke Franz Ferdinand in Sarajevo on June 28, 1914 is classified as the "trigger" of the war as it led to the ultimatum and eventual declaration of war. There were, however, many underlying causes of war, but the assassination of the Archduke is considered the most relevant single event to the onset of the conflict.

"Germany invading France" is incorrect because it should not be considered a trigger for the war. Germany invaded France as part of the Schlieffen Plan, which was in reaction to Russia mobilizing their troops on the Eastern front. 

"France breaking a treaty with Germany" and the "assassination of the German Kaiser" are incorrect because they simply did not happen.

The correct answer is the Japanese aerial attack on Pearl Harbor, Hawaii. The United States had remained neutral, aiming to avoid entering another war, until Japan conducted these aerial strikes in 1941.

"German U-boats sinking Lusitania" is an incorrect answer because that event, though it did influence the United States' involvement, occurred during the First World War. 

The Bombing of Britain did influence some United States' decision to enter because of being close allies; however, the US remained neutral throughout these desperate times in the UK. 

Germany invaded Poland in 1939, but none of the Allies aided Poland in any military or aid way despite declaring war on Germany because of this action. 

The Second Congo War occurred between 1998 and 2003 in the Democratic Republic of Congo. It is estimated that 2.5 to 5.4 million people were killed in the conflict, making it more deadly than any conflict in the world since WWII. 

The British and Soviets invaded Iran in 1941 in order to secure Iranian oil fields and make sure that the Allies would have supply lines for the Soviets fighting the Axis powers on the Eastern front. The USA was not involved in planning or carrying out the invasion. Iran was officially neutral at the time, though the British suspected Iran's leader Reza Shah of being pro-German.

With major voices such as Siegfried Sassoon, Rupert Brooke, and Wilfred Owen, the group of poets largely referred to as The War Poets became the voice of the "Lost Generation." Their works chronicled the general feelings of soldiers over the course of the four-year conflict. From jingoistic to apathetic and 'shell-shocked,' they capture the brutality and hopelessness symptomatic of the battlefields stretching from France to the subcontinent.