The word “expendable” literally means “able to be used” in the sense of “able to be used and then thrown away.” It does not necessarily mean that the item is cheap (though that might be the case). For example, consider the following: “Many packages for lunches have become expendable; people throw them away after using them instead of washing and retaining them.”

"Corroborate" means to validate or authenticate, so "validate" is the correct answer. None of the other answer choices are close in meaning to "corroborate": "execute" means to carry out a task, accomplish something, or kill someone who has been sentenced to death; "belittle" means criticize in a way that makes the person or thing being criticized seem unimportant; "debilitate" means incapacitate or disable; and "acquiesce" means to agree with some reluctance.

"Expostulate" and "remonstrate" both mean to reason with or argue. "Enervate" means to tire or wear out. "Expunge" means to destroy or obliterate. "Impinge" means to trespass or encroach. "Obfuscate" means to confuse or baffle. 

If you extol someone or something, it means you praise that person or thing.  For instance, if you extol a dancer, it means you admire or praise the dancer.

"Ascertain" means determine or find out, so "determine" is the correct answer. None of the other answer choices are close in meaning to "ascertain": "deceive" means mislead or trick; "stupefy" means stun or greatly surprise; "allure" means attract or lure; and "censor" means delete all or part of something because it is considered inappropriate.

If someone vacillates between two choices, it means they waver or are indecisive.

We often use “malign” in the sense of harmful or evil. Likewise, we somewhat regularly use the related word “malignant” to describe harmful forms of diseases like cancer. However, none of the words here fit into the category of “harmful” or “evil.” Instead, the best option is “slander,” which means to speak falsely of someone out of malice (in order to harm his or her reputation). When “malign” is used as a verb, it can mean this, more generally meaning to speak very critically and demandingly of someone else. For example, “George was horrified at how vehemently Robin maligned her sister, not merely criticizing small faults but even condemning every choice she ever made.”

"Recant" means to disavow or take back something said. "Serenade" means to sing a song or ballad. "Foster" means to promote or support. "Laud" means to give acclaim or praise. "Obscure" means to darken or make something less clear.

"Consecrate" is a verb that means "make or declare (something, typically a church) sacred; dedicate formally to a religious or divine purpose," so we will need to pick out a verb that means something like "make or declare something to be sacred." "Curse," then, cannot be the correct answer, because "curse," when used as a verb, means "invoke or use a curse against," making "curse" more of an antonym than a synonym of "consecrate." "Bless," however, is a verb that can mean "the pronouncement of words in a religious rite, conferring or invoking divine favor upon" or "to consecrate by ritual," and because "bless" is the answer choice closest in meaning to "consecrate," "bless" is the correct answer.

"Adumbrate" and "augur" both mean to foreshadow or bode. "Illuminate" means to brighten or highlight. "Conscript" means to recruit or draft. "Dote" means to cherish or fawn. "Patronize" means to support a cause or condescend to.