Something that is "smothering" is excessive to the point of causing discomfort. Something that is "overbearing"  imposes too much. "Overbearing" is the most similar to "smothering" because both refer to the characteristic of being too invasive. 

The word "minor" comes from the Latin for smaller or less. We use the word in many ways, but they generally mean small or less in a given respect. Sometimes, the word "minor" is used as a noun to describe a person who is young and not yet an adult. As an adjective, it basically means small or not important. A "minor wound" is one that is not very large, and a "minor error" is one that is not very important. When something is "insignificant," it is not of great importance. A "significant" event, on the other hand, is one that is very important. While "minor affairs" might be "dull," the word "minor" primarily indicates being unimportant or small. Therefore, "insignificant" is the best option among those provided for you in the answers.

When a person is "illustrious," he or she is widely admired or respected, usually for his or her accomplishments. This word could describe a professor who published many groundbreaking papers, or a well-liked athlete with a long and successful career. "Respected" is the correct synonym here. "Arid" refers to climate conditions that are unusually dry, while neither "playful," "sincere," or "abnormal" properly captures the admiration implied by this term.

"Understated" means modest and not drawing much attention. To be "subtle" means to be subdued and not obvious. Thus, given how similar in meaning that these words are to one another, they are synonyms.

Anything that is "vital" is absolutely required for a certain process or goal. For example, food and water are vital ingredients for human survival. "Necessary," or needed, is a strong synonym of "vital," while both "powerless" and "agreeable" are unrelated. Finally, perhaps you are unfamiliar with the final choice, "superfluous." This word simply means extra or unnecessary, which is the exact opposite of the choice we want to pick.

“Intense” means to a great degree or "extreme." The word “moderate” means in the middle of two sides or poles, whereas “mediocre” means of average quality when higher quality was expected. Something that is “effortless” does not require effort or work or is extremely easy to do, and something that is "mild" is not very strong or serious.

"Vital" derives from the Latin "vita," life, so it makes sense that something that is “vital” is very important to keeping life going, or more generally, necessary and very important. "Necessary" is thus the correct answer. As for the other answer choices, “extraneous” means not needed or part of an amount that is more than what is needed; “aggressive” means angry and violent or intense; “passive” means not doing anything in response to something; and “fatal” means deadly.

"Trifling," when used as an adjective, means "unimportant or trivial." So, we need to pick out an answer choice that means something like "unimportant." "Important" is the opposite of "unimportant," so it can't be the correct answer, but "petty" means "of little importance; trivial," "characterized by an undue concern for trivial matters, esp. in a small-minded or spiteful way" when used to describe behavior, or "of secondary or lesser importance, rank, or scale; minor." Because "petty" is the answer choice closest in meaning to "trifling," "petty" is the correct answer.

Hearty means strong and healthy. To further help you, wise means very smart, able to make good decisions; benevolent means good-natured; malevolent means wicked-natured; benevolent and malevolent are antonyms of one another; visible means able to be seen.

Something "extreme" is something that exists to a high degree. For example, extreme heat is very hot—at a high degree of heat. Extreme anger is a large amount of anger. The general idea of being extreme is this kind of largeness or greatness of amount. Thus, the best option is "enormous." None of the other options are synonymous with the idea of being of a large size or to a great degree.