An octopus has eight legs, as you might be able to infer because the word "octopus" contains the prefix "octo-" at the beginning of the word. "Octo-" means eight, and appears in other words like "octagon" (an eight-sided shape). To solve this analogy, if you don't know how many legs a centipede has, you can still arrive at the correct answer by using the prefix "cent-" as a clue to infer this information. "Cent-" means one hundred and appears in other words like "centimeter" (a unit of measurement that is one-hundredth of a meter) and "century" (a span of time of one hundred consecutive years).

A nine-sided shape is called a "nonagon," and an eight-sided shape is called an "octagon." The prefix "non-" suggests that the word will have to do with the number nine. Likewise, the prefix "oct-" suggests that the word will have to do with the number eight. (For an example of this, just think of how an "octopus" has eight legs!)

“Tertiary” is an adjective that means third, so we need to pick out an answer choice that is synonymous with “quaternary.” While all of the answer choices might look like potentially correct answers, “quaternary” is an adjective that means fourth, so “fourth” is the correct answer. You can also use prefixes as context clues to help you solve this quesiton: "tertius" is Latin for third and has influenced the prefix "tri-," while "quattuor" is Latin for fourth and has influenced English words like "quad" and "quarter."

"Microeconomics" is the study of economics on a small scale, and "macroeconomics" is the study of economics on a large scale, so the correct answer is “large.” To solve this analogy, it is important to be aware of the meaning of the prefixes "micro-" and "macro-". ­"Micro-" means small and "macro-" means big.

A triangle is a three-sided shape, which you can infer because the prefix "tri-" means three. So, to solve this analogy, you have to determine how many sides a pentagon has. The prefix "penta-" means five, so the correct answer is “five.”

The prefix ­"terra-" means related to the Earth and the prefix "celes-" means related to heaven, the sky, or outer space. As “terrestrial” is to Earth, so “celestial” is to space, so "space" is the correct answer. For clarification, “terrestrial” means of this Earth or observed on this Earth, and “celestial” means of space or observed in space or the heavens.

If you "double" something, you increase it by two-fold. The prefix "quad-" means related to the number four, so when you quadruple something, you increase it by four-fold. So, the correct answer is "four."

The prefix "pre-" usually suggest that the word will come before something or designate some beginning. In this instance, a “prelude” is an introductory event or piece of music. To solve this analogy, you have to determine which of the answer choices is something that comes after something else. The correct answer is an “epilogue,” which is the name given to a piece of writing that comes after the main narrative. None of the other answer choices make sense in the blank: “mandatory” means required; “laborious” means hard-work or exhausting; “legislate” means make laws; and “catalogue” means document and list some group of things when used as a verb and a booklet produced by a business showcasing the products that they are currently selling when used as a noun. 

The prefix "mal-" means evil or bad, and the prefix ­"ben-" means helpful or good. So someone who is “malevolent” is wicked and has a great deal of ill-will and someone who is “benevolent” is good-natured and has a lot of goodwill. So, the correct answer is "benevolent." None of the other answer choices make sense in the blank: “beneficial" means helpful; “malicious" means cruel and spiteful; “malcontent" means unhappy or not content; and “malfeasance" means something bad that someone does or a crime.

The suffix "-ible" means able to be and the roots "vis" and "aud" mean related to seeing and related to hearing or sound, respectively. “Visible” thus means able to be seen and “audible” means able to be heard, so "heard" is the correct answer.