The cardiologist is a specialist at studying the heart. The word itself as a root for “heart” in it—namely, “card-.” A “cardiac arrest” occurs when the heart suddenly stops beating. An “ecologist” is one who studies the environment, generally speaking. An ecosystem, for example, is the whole system of organisms and material environment in a given area. While each of the other options are part of the environment and animals therein, none of them is equivalent to the environment in general.

A musician performs a concert, so the answer must be something that a dancer performs. While you might think that “gyration” would work, this is a specific action, not a type of event (like concert). Thus, “ballet” is the best answer for this. Even though all dancers do not necessarily perform ballets, this option alone establishes a parallel with dancer in a manner similar to the relationship between musician and concert.

"Cardiovascular" is a medical term relating to the "heart," just as "pulmonary" refers to the "lungs."

When a person suffers from malnutrition, that person lacks sustenance to support his or her life. The “mal-” prefix should indicate this to you, as it expresses “poorly” or “lacking.” The word “sustenance” can be thought of as a “sustaining amount of food.” Thus, the analogy could be rewritten, “As someone suffering from malnutrition lacks sustenance, so does someone or something suffering from desiccation lack X.” Desiccation is the state of being completely dry and lacking fluid. 

Annoyance is a type of emotion. Therefore, we are looking to find a word that expresses a "type-of" relationship. Cannons are a type of implement used for warfare. Therefore, they are a type of "armament." The word "arms" often are used to describe such military equipment, as when people speak of "arming" a group for battle.

A civilian is a person who exists in a city in a non-military capacity. When used as an adjective, the word "civilian" is well contrasted to "military." The best answer is therefore the simple word "soldier." The civilian is not contrasted directly to the ruling class—hence both "senator" and "president" are not good answers.

A "thrall" is a servant or slave to someone else. We often will also use this word in an expression like, "Peter was in thrall to his uncontrolled desire for chocolate." This means that Peter was a slave to his stomach—to his desire and love for chocolate. In contrast to this, the word "lord"—simple though it may be—is the best option. The only close option is "viceroy," which describes someone who rules in the stead of the main sovereign. We need a word that directly signifies being a lord or ruler, however, and to this end, the simple "lord" works best.

To be intimate with someone is to be close with that person. Generally speaking, when people are called "intimates," they are considered to be friends. The first contrast that comes to mind, therefore, is likely "enemies." While we do not have this as an option among the words provided for answers, we do have "adversaries," which basically means "opponents." The word comes from roots meaning turned against one another.

When used in the plural, the "heavens" are merely the sky—as in the whole contents of space. Because of the Judeo-Christian usage "heaven and hell," you are likely tempted to pick "inferno" or even "condemnation." However, the best antonym for the simple word "heavens" is the equally simple "ground." The contrast here is "heaven and earth."

A "deluge" is a flood. It is very hard to find a tangible opposite to a flood, but we can consider the situation in which there is a lack of water. This would provide a decent antonym for us—enough to answer this question at least. Precipitation is something potentially wet (if it refers to rain or snow), and a draft does not directly signify being dry. The other two options are abstract states that do not apply to this question at all. Therefore, the best answer is "drought," describing a period of dry weather without any rain—quite the opposite of a deluge.