"Potent" is an adjective that means "having great power, influence, or effect," so we need to pick out an adjective that means something like "powerful" or "having a strong effect." "Frail," then, cannot be the correct answer, because "frail" is an adjective that can mean "of a person: weak and delicate," "easily damaged or broken; fragile or insubstantial," or "weak in character or morals," making it an antonym, not a synonym, of "potent." "Mighty," however, is an adjective that can mean "possessing great and impressive power or strength, especially on account of size" or "of an action: performed with or requiring great strength." Because "mighty" is the answer choice closest in meaning to "potent," "mighty" is the correct answer.

"Potent" means powerful; Unfortunate means unlucky; Immortal means able to live forever; Memorable means easily remembered; and Critical means important.

"Drowsy" means sleepy or tired.

Something that is "intricate" is complex and complicated. For clarification, an "outlier" is something or somebody that is outside of the norm; "serendipitous" means owed to good fortune.

"Potent" means forceful or powerful, so "powerful" is the correct answer. "Weak" is an antonym of "potent" and "powerful"; it means not having strengh or power. "Disappointed" means upset or not having one's expectations met. "Idiotic" means stupid or foolish. "Flawless" means perfect or without defects.

"Torpid" means inactive or lacking energy. While not precisely synonyms, "functional" and "active" have similar meanings. You can eliminate them. "Dynamic" and "vital" are synonyms meaning full of energy. Therefore, the only choice that fits is "dormant," which means inactive.

"Feeble" is an adjective that means lacking strength. Of the answer choices, "weak" has the closest meaning.

"Grueling" means very tiring or exhausting, so "exhausting" is the correct answer. "Lively" is an antonym of "grueling" and "exhausting"; it means active or having a lot of energy. "Immature" means child-like, as one might infer from the word being a combination of the negative prefix "im-," which means not, and "mature." "Contagious" means easily spread and usually refers to a disease. "Diligent" means hard-working.

"Futile" means of no use or pointless, so "pointless" is the correct answer. "Purposeful" is an antonym of "futile" and "pointless"; it means determined or doing something with a goal in mind. "Distant" means faraway. "Endless" means having no end or limit. "Glamorous" means lovely or alluring.

"Invincible" means unbeatable. "Weak" means having little power, strength, or energy, so it is an antonym, not a synonym, of "invincible." None of the other answers are close in meaning to "invincible": "humble" means not vain or modest; "cautious" means careful; and "obedient" means loyal and obeying directions.