The correct answer is "powerful landed nobility" because, having defeated the other tribal leaders, the Sultan of the Ottoman Empire was able to rule arbitrarily as a single individual without being tempered by a landed nobility.

The Inca Empire was founded in 1438. The vast majority of Inca territory was conquered by the Spanish by 1533; therefore, the Inca Empire lasted for ninety-five years, a little less than a century.

Suleiman the Magnificent, whose reign as Sultan lasted for over forty years, is today regarded as perhaps the single most successful ruler of the entire Ottoman Empire. Suleiman first came to the throne in 1520 and almost immediately, he embarked upon a vastly ambitious campaign to expand his nation’s territorial holdings. A brilliant strategist and a fierce warrior in his own right, Suleiman amassed a truly impressive military force, replete with highly-skilled soldiers and a substantially fortified navy. Throughout his long reign, Suleiman continually conquered, annexed, and/or attempted to conquer different sections of territory across Europe, the Middle East, Asia, and Africa. In most cases, he was quite successful – he captured much of Hungary, Belgrade, Rhodes, and large swathes of Northern Africa (including Algeria and Tunisia), among many others. His one notable defeat occurred in 1529, when he besieged the vital Austrian city of Vienna but failed to capture this crucial entryway into Eastern Europe. This defeat put an end to Suleiman’s European territorial gains.

The Delhi Sultanate began in 1206 and, within a century, had expanded to dominate the vast majority of the Indian subcontinent. Over the next two centuries, however, the Sultanate would gradually lose territory — as city-states in the south revolted and declared their independence and as invaders from the north (like Timur) repeatedly invaded and weakened the power of the Sultans.

The Meiji era lasted from 1868-1912 and was the era that led to the development of Japan as a modern world power, this set the stage for their involvement in World War I and II. The Tokugwa government was the final feudal government that ruled Japan; it lasted from 1603-1868 (the beginning of the Meiji Era). The Heian period is considered part of classical Japanese history; it lasted from 794-1185. The Showa period lasted from 1926-1989. The Kofun period lasted from 250-538.

The Berlin Conference divided Africa amongst the European powers for economic gain and paid no attention to the pre-existing social structures. This is believed to be the cause of many of the continent's problems that persist today. 

'Manifest Destiny' was a driving force behind American westward expansion during the nineteenth century. Developed early in the century, ideology established that the duty, and ultimate goal of American expansion was to build a country spanning the land between the Atlantic and Pacific oceans.

During the Meiji restoration, Japan was able to successfully modernize and adapt in the face of encroaching European colonialism, eventually building its own empire. Unlike the other states listed, the Japanese process of post-1868 modernization was maintained through the mid 20th century, continuing, in various forms, to the present day, with Japan being a leading figure in many technology-related fields (especially robotics).

The Proclamation of 1763 declared it illegal for colonists to settle west of the Appalachian Mountains. This caused much tension because the colonists saw this land as theirs now that they had won it from the French. The British crown, however, wanted to keep the land for the Native Americans so as to give the displaced East Coast tribes a new home and dissuade them from engaging in conflict with the colonists over land.

The Sugar Act was the first of many acts by Parliament meant to recoup the money the British had spent defending the colonies during the Seven Years War. This one placed a tax on sugar and molasses, two frequently used goods in the colonies.