To be adept at something is to be skilled or good at it. To further help you, tropical means having a warm and wet climate; frigid means very cold; stifling means very hot and restrictive; challenging means difficult.

When something is "captivating," it is able to take someone "captive"—at least figuratively speaking. That is, it captures your attention because of its forcefully interesting character. Sometimes, the word can be used as a positive description of someone (a captivating personality). Generally speaking, the best use of the term is one that indicates forceful capturing of attention. Therefore, the best option among those provided is "enchanting." Something "enchanting" is very attractive or charming. Such enchanting things are able to capture someone's attention as well. Hence, they are rightly called "captivating."

When you hear the word "brazen," you might think of the similar-sounding word "brave." The terms are similar, as both refer to fearless behavior, but "brazen" is a little bit more specific. While a brave person might be courageous in a number of situations, someone who acts in a brazen manner is shameless about doing things that would make other people embarrassed. "Bold," a word that can indicate both confidence and a disregard for rules, is our best choice here. Someone who feels shamelessly confident would not be "embarrassed," "nervous," or "powerless," so those choices are incorrect.

"Fickle" is an adjective that means "changing frequently, especially as regards one's loyalties, interests, or affection," so we need to pick out an answer choice that means something like "changing frequently." "Constant," then, cannot be the correct answer because "constant" is an antonym of "changing frequently." "Inconstant," however, is an adjective that means either "frequently changing; variable or irregular," or when used of a person or their behavior, "not faithful and dependable." Because "inconstant" is the answer choice that is closest in meaning to "fickle," "inconstant" is the correct answer.

If you have heard "avid" used in phrases like "an avid sportsman," you might be able to figure out that "avid" means eager, or very interested in something. So, "eager" is the correct answer. "Apathetic," "indifferent," and "passionless" are all antonyms, or opposites, of "avid."

"Presumptuous" is an adjective that is used of a person or their behavior and means "failing to observe the limits of what is permitted or appropriate," so we need to pick out an answer choice that means something like "not appropriate." "Apt," then, cannot be the correct answer because "apt" means "appropriate or suitable in the circumstances," making it an antonym, not a synonym of "presumptuous." "Audacious," however, is an adjective that means either "showing a willingness to take surprisingly bold risks," or "showing an impudent lack of respect." Because "audacious" is the answer choice that is closest in meaning to "presumptuous," "audacious" is the correct answer.

Someone who is "adaptive" is good at adjusting to his or her surroundings. Someone who is "flexible" is able to accommodate different types of situations. Therefore, "adaptive" is most similar to "flexible."

Someone who is “deft” is very skillful at a particular activity. Something that is “harmful” is damaging. Something that is “overt” is obvious, palpable, or not at all hidden.

"Chatty" is the adjectival form of the word "chat," which means talk casually about relatively unimportant subjects. Someone who is "chatty" likes to chat, so they are "talkative." "Fluent" may look like a potentially correct answer, but someone "fluent" in a language is able to speak that langauge very well, so it is not close in meaning to "chatty."

Someone who is “stern” is very strict and serious, so "stern" is closest in meaning to “severe,” a word that means very serious.