"Vicious" means brutal or "violent." "Helpful" means a person who assists others or is supportive. "Cooperative" means able to work well with others. "Obedient" means compliant or willing to follow the orders or others. "Stubborn" means not willing to change one's viewpoint or course of action.

Someone who is "intrepid" is very enterprising and adventurous. For clarification, "timid" means shy and reserved; "ingrained" is something embedded or inbuilt; "susceptible" means vulnerable.

"Congenial" means agreeable or friendly, so "agreeable," which means pleasant or amenable to something, is the correct answer. For clarification, "avaricious" means greedy, "portentous" means self-important or ominous, "generous" means liberal in giving, and "disagreeable" means not agreeable or unpleasant, as one might be able to infer from the word being a combination of the negative prefix "dis-" and the word "agreeable."

"Devious" is an adjective that means "showing a skillful use of underhanded tactics to achieve goals," so we need to pick out an answer choice that means something like "underhanded." Naïve," then, cannot be the correct answer, because when used to describe people, naive either means "showing a lack of experience, wisdom, or judgment," or "natural and unaffected; innocent," neither of which is synonymous with the meaning of "devious." "Deceitful," however, is an adjective that means "guilty of or involving deceit; deceiving or misleading others," and because "deceitful" is the answer choice that is closest in meaning to "devious," "deceitful" is the correct answer.

"Impudent" means boldly rude. "Urbane" and "debonair" both mean polite and sophisticated. Here's a hint: when solving synonym questions, eliminate answer choices that are synonyms of each other. "Timid" means shy, and "reticent" means not saying much. So, "sassy," which means cheeky, is the answer!

“Negligent” is an adjective that means “failing to take proper care,” so we need to pick out an answer choice that means something like “not doing something carefully.” That means that “responsible” cannot be the correct answer, because “responsible” means “capable of being trusted,” making it an antonym, not a synonym, of “negligent.” “Lax,” however, is an adjective that can mean “not sufficiently attentive,” and because “lax” is the answer choice closest in meaning to “negligent,” “lax” is the correct answer.

"Surly" means "rude or hostile," irritable. 

"Humorous" means being funny or comical.

"Jumpy" means nervous or subject to sudden, involuntary starts.

"Stubborn" means headstrong, or unreasonably set in purpose or opinion.

"Ignorant" means lacking in knowledge or training.

"Enigmatic" means "puzzling" or mysterious.

"Deceitful" means prone to lying or deceit.

"Mischievous" means maliciously or playfully annoying.

"Stupid" means lacking ordinary mental quickness.

"Untrustworthy" means not deserving or trust or confidence.

"Unscrupulous" means "without conscience" or unprincipled.

"Stern" means strict, harsh, or uncompromising.

"Cruel" means willfully or knowingly causing pain or distress to others.

"Malicious" means intentionally harmful or spiteful.

"Devout" means sincerely religious, earnest, pious.

"Courteous" means "polite," well mannered or respectful.

None of the other words are synonyms of courteous:

"Exuberant" means to be filled with excitement.

"Flirtatious" means to suggest playful attraction to someone.

"Princely" means splendid or related to a prince.

"Restrained" means unemotional, moderate and reserved.