"Foster" means to "promote growth" or to nurture or to support something.

"Eradicate" means to eliminate or destroy or remove.

"Polarize" means to divide into opposites, to split.

"Renounce" means to abandon, to reject, to quit.

"Stifle" means to suppress, to restrain, or to prevent from expanding or growing.

The verb "covet" means to want to possess something, to yearn for something, to "desire" something.

The verb "repress" has several different meanings, all of which are loosely related. It can mean to put down an uprising or protest; it can mean to prevent or restrain; it can mean to control and suppress; or it can mean to push down one's emotions so that they are subconscious and concealed. Additionally, "ordain" means make holy or formally approve of; "dispute" means argue against a certain point; "deride" means mock, speak negatively about and make fun of; "assume" means believe something to be true without actually knowing.

"Fret" means to "worry," to agonize, or to brood.

"Sanction" means to authorize, approve or certify.

"Repudiate" means to abandon something, to turn one's back on, to reject something.

"Scorn" means to feel contempt, to sneer or to disdain.

"Appease" means to satisfy, to pacify or to alleviate.

"Incite" means to encourage, to provoke, or to rally people.

"Connote" means to signify, to mean, or to hint at.

"Devise" means to come up with, to concoct, or to mastermind. 

"Diagnose" means to identify a disease or an issue, to determine, to investigate.

"Rescind" means to declare null and void, to cancel or to dismantle.

"Exhort" means to "warn," to advise, or to admonish.

"Chastise" means to scold, to tell off, to reprimand.

"Extol" means to sing the praises of, to celebrate, to commend. 

"Concur" means to agree or to approve.

"Deter" means to inhibit something or someone, to stop them, to obstruct them.

"Petrify" means to terrify or to scare someone so badly that they can't move; "petrify" can also mean to become inert or fossilized.

"Convince" means to assure or persuade someone.

"Welcome" means to receive someone, to accost someone or approach someone with a greeting.

"Malign" means to defame, besmirch, or denigrate something.

"Encourage" means to stimulate, to boost or to buoy someone's confidence; to give someone courage.

Elicit means to draw out.

"Behoove" is a verb that means "to be necessary, proper, or advantageous for," so we need to pick out another word or phrase that has a similar meaning. While "decorous" might look like a good answer choice because "decorous" means "proper," "decorous" is an adjective while "behoove" is a verb, so "decorous" cannot be the correct answer. Because "be proper for" is closest in meaning to "behoove" of the given answer choices, "be proper for" is the correct answer.

"Dovetail" is a verb that means "to fit together in a pleasing or satisfying way," so we need to pick out another word that means "to fit together well." While "combine" means "unite" or "merge," it does not include the positive connotation that "dovetail" does in that "merge" does not necessarily entail two things combining "in a pleasing or satisfying way." "Harmonize," however, besides meaning "to play or sing different musical notes that sound pleasing together," also means "to be combined or go together in a pleasing way." Because "harmonize" not only means "combine" but also includes the positive connotation of "in a pleasing way," "harmonize" is the best answer.