Several of the options try to make you think of "stock" in the sense of "stock market" or the "stock in a store." None of the options, however, function as antonyms even for these meanings of "stock." The word can also mean "ordinary," as in, "He used all of the stock tricks when giving the magic show"—meaning that the magician was not too amazing. It is as though he or she took out the basic tricks from the "stock" that he or she had. Hence, the best antonym for this use of "stock" is "unusual."

The adjective "consummate" describes something that is the best in a given category—or at least one of the best things in that category. If nothing else, it indicates that something is flawless or perfect. The "consummate pianist" is someone who is a great pianist. In contrast to this, the word "flawed" is an excellent antonym.

Something is called "economical" when it is priced in a way that gives the most value per dollar. For instance, a car that is cheap, small, gets good gas mileage, and requires little maintenance is quite economical. In contrast to this, something exorbitant is very expensive—often to the point of making little financial sense. While we might think of better antonyms than this, of the options provided, this is the best match, for the others do not function as antonyms in any proper sense. (However, some options like "familial" and "laborious" attempt to trick you into thinking these things are contrasted to the "economy" in the sense that we normally use that word.)

Something that is "mediocre" is merely "okay" in its quality—often even implying that it is not of very good quality at all. A number of the options provided are meant to trap you into a wrong answer. Something that is excellent—the opposite of mediocre—might indeed be "surprising," "famous," or "unexpected." However, the best option is "exemplary," a word which describes something that is very excellent—to the point of being an "example" or standard for other things of a similar type. This best captures a direct opposition to mediocrity.

Among humans, peers are people who are "equal." To be "peerless" means to be without anyone or anything that is your equal. A "peerless diamond" is one that is of such quality or beauty that it cannot be matched by another. Therefore, the word "peerless" means unrivaled. A convention is a generally held belief or practice, and something that is "conventional" is done in accord with such general beliefs or practices. Such things are very ordinary and repeatable. This is quite different from something that we would call "peerless."

The adjective "scant" means of little amount to the point of being insufficient. To give "scant attention" to something is to pay very little attention to it, and to say something is "a scant three gallons" means that it is barely three gallons. In contrast to being barely enough, an excellent antonym is "abundant", meaning plentiful.

The word "negligible" is related to the word "neglect." We tend to neglect something that is not very important to us. Something "negligible" is very small and insignificant. In contrast to this, something "significant" is important. A "significant amount of time" is a good deal of time, and a "significant event" is one that is important.

The word "senescent" is related to roots from which we get words like "senior" and "senator," the latter really describing a person who is supposed to be old and wise. To be "senescent" is to be aged, often with the effects of deterioration that come with the passage of time. Although the word "adolescent" can be a bit negative, it does not have to be such. It can merely mean that someone is in the period of youth in which he or she is passing to adulthood. Among the options provided, this is the best temporal contrast to "senescent."

When someone "plods along," he or she moves at a slow speed, often as though he or she has a heavy burden on his or her back. Do not be tempted to pick an answer like "joyous." Just because someone is plodding, he or she does not necessarily do this because of being depressed or sad. The best antonym is "expeditious," meaning done quickly and efficiently. To "expedite" a process is to make it happen more quickly.

The word "inanimate" comes from the Latin root meaning to have a soul. We generally refer to things as being "animated" when they move, seeming to have self-motion. An "animate" being is one that is living. The most tempting wrong answer given for this question is "biotic," which means relating to living things; however, this does not describe the living thing itself. The best answer—as homely as it might seem—is "living."