A "conundrum" is something that is very difficult to understand. The best choice is "enigma," which means a person or thing that is very difficult to understand. Considering the other choices, "instrument" means an object or tool used to perform a task, often specifically to perform music, "cusp" means edge, and "enlightenment" means the state of having gained knowledge.

Things that you have an "aversion" to are things that you have a dislike for, so "dislike" is the correct answer. None of the other answer choices are close in meaning to "aversion": "promote" means support or speak positively about; "retire" means stop working and usually receive benefits after having worked for a very long time; and "suffer" means experience pain and sadness.

A "prophesy" is a prediction or forecast of the future, so "prediction" is the correct answer. None of the other answer choices are close in meaning to "prophecy": "domicile" means the location at which a person lives permanently; "reign" means the period during which a ruler rules; "obesity" means the medical condition of being overweight; and "insomniac" means someone who regularly has difficulty sleeping.

"Incentive" is something that motivates or gives a person a reason to do something, so "motivation" is the correct answer. None of the other answer choices are close in meaning to "incentive": "proximity" means closeness or nearness; "boundary" means a line that marks the extent of a region or territory; an "oration" is a formal speech; and a "compliment" is a remark that shows admiration.

Something that is "delectable" causes delight, often in relation to one's sense of taste. The word is a favorite of bakers in describing their pastry creations. The word is not related to the word "derelict" (abandoned or negligent).

"Epoch" means era or period of time, so "era" is the correct answer. None of the other answer choices are close in meaning to "epoch": "riddle" means a verbal puzzle; "insomnia" means a condition in which one cannot sleep; "option" means choice or alternative; and "summit" means apex or the highest point of something.

"Epoch" means a period of time or era, so "era" is the correct answer. None of the other answer choices are close in meaning to "epoch": "debris" means trash or wreckage; an "enigma" is a puzzle or riddle; "literacy" means the knowledge of how to read and write; and a "nomad" is a wanderer or vagrant.

"Peril" is an noun that means significant danger, so "danger" is the correct answer.

"Stamina" is a word often seen in an exercise context and it means "endurance" or the ability to persevere. "Resignation" is giving up; "transience" is something that is fleeting; "reluctance" is unwillingness; and "spirit" is enthusiasm.

"Elation" is a feeling of deep happiness, so "happiness" is the correct answer. It is an antonym of "sadness." To help you, "ambivalence" means uncertainty or the presence of conflicting ideas, "despondency" is a feeling of hopelessness and sadness and is almost the complete opposite of "elation," and "frivolousness" means the quality of being unnecessary and wasteful.