“Stationary” means unmoving as opposed to in motion, so "unmoving" is the correct answer. As for the other answer choices, “staunch” means committed and firmly supporting; “frosty” means cold; “stern” means strict and sticking to the rules; and "fluid," when used as an adjective, means either flowing or in a liquid form.

The word "sporadic" means happening at irregular intervals in time. The best choice is "intermittent" because it shares the same definition. Considering the other choices, "arboreal" means having to do with trees, "spartan" means self-disciplined and apathetic about comfort, and "burdensome" means troublesome.

"Permanent" means lasting forever or for a very long time or not erasable. To provide further guidance, "insipid" means boring or dull, "optimal" means perfect or prime, and "coherent" means able to be understood.

Transient most nearly means temporary. Something that is "transient" is passing or fleeting. As a noun, the word most nearly refers to a vagabond. For example, "her feelings were transient."

The other choices are antonyms, with the exception of "peaceful," which is unrelated.

"Obsolete" means outdated or no longer in use, so "outdated" is the correct answer. None of the other answer choices are close in meaning to "obsolete": "modern" is an antonym of "obsolete" and means new or up-to-date; "stubborn" means refusing to change one's attitude or viewpoint despite evidence to the contrary; "pious" means devout or very religious; and "wretched" means miserable or very sad.

Something that is "obsolete" is no longer useful or out of date, so "out of date" is the correct answer. To help you, "fecund" means fertile, "demonstrative" means openly showing how one feels, especially concerning being fondness, and "prolific" means productive, creative, or fecund.

The literal meaning of “antediluvian” is from the time before the biblical flood. However, in conventional English it is used to refer to anything extremely old-fashioned and outdated. So, "very old" is the correct answer.

"Furtile" means producing vegetation or crops or able to have children, so "fruitful" is the best match. "Barren" means failing to produce fruit or unable to have children and is an antonym of "fertile."

"Prone" is defined as lying flat or lying flat while facing downward, so "reclining" is the best choice. "Upright," which means vertical, has the opposite meaning.

The word "rustic" means pertaining to the countryside or simple and plain. The best choice is "simple" because it is a part of the definition of "rustic." Often, simplicity is associated with the countryside, while complexity and sophistication is associated with the city. Considering the other choices, "rusted" means coated with rust and corroded, "metallic" means consisting of or resembling metal, and "turbulent" means tumultuous or stormy.