"Withstand" is a verb that means either resist successfully or not take any damage from. We need to pick out an answer choice that means something like resist. "Succumb," then, cannot be the correct answer, because "succumb" is a verb that means intend to resist but fail to do so, making it an antonym of "withstand," not a synonym. "Resist," however, is a verb that means endure, and because "resist" is the answer choice closest in meaning to "withstand," "resist" is the correct answer.

To "fortify" something is to reinforce it, which means to make it stronger. For a classic example, think about a building, like a castle. You could fortify the castle by building extra walls and defensive structures, which would strengthen it against attack. As for the other answer choices, "deteriorate" means fall apart, "corrupt" (when used as a verb) means make worse in quality or less moral, and "maintain" means keep something in the same condition.

There are two definitions of scour.  In this definition, it means to polish or clean.  The other meaning of scour is to search thoroughly.

To "writhe" means to twist, usually in pain, so "twist" is the correct answer. To help you, "abolish" means get rid of, "admonish" means criticize or punish for doing something wrong, "intercept" means interrupt something intended for someone else, and "delay" means pause when used as a noun, and to "delay" something is to put it off until a later time.

"Impede" is a verb that means "delay or prevent (someone or something) by obstructing them; hinder," so we need to pick out an answer choice that means something like "delay" or "hinder." "Permit," then, cannot be the correct answer, because "permit," when used as a verb, means "give authorization or consent to (someone) to do something," a meaning that is not similar to "delay" or "hinder." "Hamper," however, is a word that when used as a verb, means "hinder or impede the movement or progress of," and because "hamper" is the answer choice closest in meaning to "hinder," "hamper" is the correct answer.

Knead means to work or mold a substance with one's hands. Massage means to rub or work with one's hands as well, and thus is the closest in meaning. While kneaded dough is often baked, bake is not a synonym. The words are related, but not the same in meaning. 

Accelerate means to increase in speed. Quicken means to go faster. Given these definitions, accelerate and quicken are very close in meaning, and therefore synonyms of one another. 

Hoard means to find and keep large amounts of certain types of objects. Collect means to form a grouping of particular items. Thus, given how similar these words are, they are synonyms for one another. 

When you "refine" something, it means that you "improve" it compared to its original condition. This differs from "glorify," which means to raise in status; "regard," which means to see or think of someone in a certain way; and "reward," which means to give compensation for a job well done.

The word "plunge" has a range of meanings, but all of them have to do with falling in one way or another.  When the prices of something plunge, they fall quickly and greatly. When you plunge a knife into a tomato, you press it into ("down into") its surface. Likewise, when you go for a swim and dive into the water, you plunge down into the water.  It is in this sense that the word is being used here, so the best option is "dive," which alone is a good synonym for "plunge."