"Candid" means impartial, open, or honest. "Caustic" means burning or sarcastic. "Corporal" means bodily or physical. "Prevalent" means accepted or widespread. "Ubiquitous" means ever-present or pervasive. 

"Windfall' is a noun that is defined as "an unexpected, unearned, or sudden gain or advantage" or "a piece of unexpected good fortune, typically one that involves receiving a large amount of money." While "trip" may sound like a potentially correct answer because "windfall" is created from a combination of the words "wind" and "fall," "windfall" does not mean "to knock something over with wind" or have anything to do with falling, so neither "blow over" nor "trip" can be the correct answer. "Jackpot," a noun meaning "a large cash prize in a game or lottery, esp. one that accumulates until it is won," is the closest synonym to "windfall" amongst the listed answer choices, so it is the correct answer.

Although “bewilder” is a verb, we often use it in its perfect passive participle form, “bewildered,” or in its present active participle form, “bewildering.” When it is used in the former sense, it means perplexed or confused. For example, we can say, “He was utterly bewildered by the questions being asked by the child, for he could only understand the sorts of questions asked by people who were his own age.” When used as a verb, “bewilder” merely means to cause confusion or perplexity. For example, one could say, “Questions bewilder the man and make him extremely confused and angry.”

The word “vacillate” is akin to “oscillate,” meaning “to sway or swing.” In the case of vacillate the “swinging to and fro” is implied as being between two options. It is a person who vacillates, not a pendulum. For this reason, it means something like “hesitate” or to be “ambivalent or undecided.” For example, you could say, “After considering both sides of the argument, Maria could not help but vacillate between choosing either option, for both seemed very appealing.

The word “abate” most directly means to become less intense. For instance, one could say, “Although Robert was quite angry at his friends, with time, this emotion abated, being replaced with a much calmer state of mind.” In its English origins, the word had a legal usage meaning to put a stop to. Since “abate” distantly has a root in the Latin for to beat, the word could be taken (in a broader sense) as indicating the beating back of something intense.

When someone is “overwrought,” that person is excited or anxious. While that might cause someone to be jittery or even annoying, the best option among those given is the mere direct definition, “anxious.” The word would be used in a sentence like, “Having arrived at the long-feared day, Jonathan was so overwrought that he could not even sleep because of his agitated nerves.”

You might confuse “prodigal” with “prodigy” or “prodigious.” The former means “being very talented,” especially when that person is very young. For instance, one can speak of Mozart as being a “child prodigy,” having shown great musical talent from his youth. Something “prodigious” is impressive and of great magnitude. When something is “prodigal,” it is “great” in the sense of being wasteful. The Biblical story about the “Prodigal Son” is about a son who spends all of his money wastefully before coming home to seek forgiveness. He is called “prodigal” because of this wastefulness.

"Sagacious" and "astute" both mean smart or judicious. "Arrogant" means haughty or overly proud. "Barefaced" means shameless or open. "Complaisant" means agreeable or easy-going. "Effluent" means drainage or outflow. 

The definition of "mundane" is everyday or ordinary, making "common" the only possible choice.

You might be more familiar with the word “platitude” than with “platitudinous.” The former is the related noun form of the same base. A “platitude” is an expression, often moral in nature, that has been so overused that it has lost its meaning. You might know someone who recites such expressions as, “Everything happens for a reason.” Such remarks either tell you nothing or often just frustrate you when horrible things happen. They provide little consolation or direction. Although a “platitudinous” expression could be called “annoying,” it is most properly said to be something “overused.” The annoyance follows on the fact that overuse has totally shorn it of its meaning and significance.