The prefix "re-" means back or again, and "pel" derives from a Latin root meaning force, so it makes sense that "repel" means force back, deflect, or "repulse." “Summon” means send for or call for; “beckon” means wave for someone to approach; “command” means order or tell what to do; and "intrude" means interrupt, often by entering a space in which one's presence is not desired.

The prefix "im-" means not, and the Latin root "mort" means death, so it makes sense that "immortal" means not mortal, or not able to die. This makes "eternal," which means lasting forever, the correct answer. As for the other answer choices, “effortless” means not requiring effort or done with such skill as to make look extremely easy; “laborious” means difficult and involving hard work; "inconclusive" means not supporting any definite conclusions; and "frequent" means occurring often.

"Ob-" is a prefix that often means against, and "-ject" derives from roots that mean throw. (Other English words that include "-ject" include "inject," "subject," "project," and "reject.") So, it makes sense that "object," when used as a verb, means argue against something and prevent it from proceeding. Conversationally, "objecting" to something is like "throwing yourself" against it to try to stop it or prove it wrong. The word is often used in court when someone wants to stop the proceedings because he or she disagrees with what has been said or how something has been said. "Oppose," which means be against and dispute, is thus the correct answer choice.

As for the other answer choices, “theorize” means to think and suggest why something is; “project,” when used as a verb, means predict or protrude; “concur” means agree; and "falter" means momentarily pause, stumble, or have one's resolve shaken.

The prefix "co-" means together, "labor" means work, and the suffix "-ate" means make or do,  so it makes sense that "collaborate" means work together, especially on a project. "Cooperate," which also features the prefix "co-" and means work together without causing each other trouble, is thus the correct answer. As for the other answer choices, “conversation” is talking with another person; “training” means preparation or working to get better at something; and a “demonstration is an instance of showing how something is done by having someone do it; and "simplicity" is ease or the lack of complication.

The prefix "ob-" means against, so it makes sense that "obscure," when used as an adjective, means hard to understand or unknown, making “unclear” the best answer choice. As for the other answer choices, “certain” means sure; “assured” means confident, feeling calm and sure; “responsive” means reacting to stimuli; and “relevant" means pertaining to the subject of something or the matter at hand.

The prefix "pre-" means coming before, so it makes sense that "prescience" means knowledge about what is coming in the future, or “foresight." As for the other answer choices, “ignorance” means cluelessness or lack of understanding; “nostalgia” is a feeling of fondness about the past; “prowess” means skill; and “account” means story, version of a story told by a specific person, ledger of money withdrawn and deposited at a bank, or password-protected personal identity on a website.

The prefix "in-" means not, and "credible" includes the root "cred-," suggesting it has something to do with belief like other words that contain this root, like "incredulous" (surprised at something that seems unbelievable). "Credible" by itself means believable or trustworthy, so it makes sense that "incredible" means not able to be believed or surprising. This means that "unbelievable" is the correct answer. As for the other answer choices, "untouchable" means unable to be touched; “edible” means able to be eaten; "pardonable" means able to be pardoned or excused; and "workable" means potentially successful or able to be worked with.

The prefix "im-" means stop or not, and "mobilize" means make able to move or prepare and deploy military troops and units, so it makes sense that "immobilize" means make unable to move or continue. As for the other answer choices, "dissolve" means melt away or, more precisely, put a solid into a liquid solution such that it breaks apart at the molecular level and is no longer visible to the naked eye; “form," when used as a verb, means shape or make; and “function,” when used as a verb, means work.

The prefix "eu-" means good, so it makes sense that "euphoria" is a feeling of great happiness; this means that "elation" is the correct answer, as "elation" also means great happiness. A “district” is a distinct area in a larger area, often in a city; “despair” is hopelessness; “desolation" means despondency, loneliness, or emptiness; and “judgement” means an official decision about a disputed issue, often from an authority figure.

The prefix "ex-" means outside or beyond, and the "-cede" portion of "exceed" derives from a Latin word that means go, so it makes sense that "exceed" means go beyond or do more than you need to. “Surround” means cover or be all around something; “defend” means look after or protect; and “announce” means declare information publicly for the first time.