When you "compute" something, like a math problem, you "calculate" the answer to that problem. As for the other answer choices, when used as a verb, "reason" means to use logic to solve a problem; "discover" means to find; and "signify" means to express or have one thing stand for another.

"Preoccupy" is a verb that is used of a matter or subject and means "dominate or engross the mind of (someone) to the exclusion of other thoughts." So, we need to pick out a verb that means something like "engross." That means that "forget" cannot be the correct answer, because if someone forgets something, that means that it cannot preoccupy their thoughts. "Absorb," however, is a verb that means "absorb all the attention or interest of," and because "absorb" is the answer choice closest in meaning to "preoccupy," "engross" is the correct answer.

The word “demonstrate” means to show how something is done by doing it yourself as an example, so the correct answer is “show.” The word “possess” means to have; the word “compete” means to face someone in a competition; and to “allow” something means to let it happen without trying to prohibit it or stop it.

To “gaze” at someone or something means to look at them for a long time, so it is closest in meaning to “stare.”

To "instruct" means pass on information or a skill. This is very close in meaning to the verb "teach." Thus, "teach" is the best synonym. The other words are unrelated to the act of instruction.

"Persuade" means to make someone believe a particular opinion or way of thinking. "Convince" means to get a person to take on certain thoughts or ideas as their own. Given how similar these words are in meaning, they are synonyms, and "convince" is the correct answer.

To "advertise" means to spread the word about something, often a product people can buy. Similarly, to "publicize" means to put something in the public eye. Putting something in the public eye will certainly spread the word about it. Therefore, "advertise" and "publicize" are synonyms.

When people or groups "cooperate," they work together to achieve a common goal. Since "unite" means come together, this verb is the most relevant choice. When we take a look at the other three answers, we can see that both "disagree" and "compete" refer to actions that do not involve working together in harmony. Finally, to "startle" another individual is to surprise him or her, so that term has nothing to do with our original word.

To "describe" means to portray what something is. The word that best matches this is "explain," which means to discuss something in detail so one's listeners better understand that thing. Therefore, it is the correct answer. The other words are unrelated to this.

To “indicate” means to show something or to explain to someone how something should be done or understood. The word “mock” means to make fun of, and the word “reckon” means to think or to think something is true.