Correct Answer: C

Rationale: When someone is at the zenith of their career, it means they have reached the highest point or peak of success in their professional life. This suggests that they have achieved their utmost potential and are enjoying the height of their career accomplishments. Choice A, 'just getting started,' is incorrect as it implies the beginning of a career rather than the peak. Choice B, 'preparing for retirement,' is incorrect because being at the zenith of one's career usually signifies the prime of one's professional success, not the preparation for retirement. Choice D, 'having trouble with your superiors,' is incorrect as it is unrelated to the concept of reaching the peak of success in one's career.

Correct Answer: D

Rationale: In this sentence, the word 'tumult' is used to describe a state of confusion, disorder, and chaos in the emergency room. 'Commotion' is the closest synonym to this meaning, making it the correct choice from the list provided. Choice A, 'Siren,' does not capture the meaning of chaos and disorder. Choice B, 'Distress,' refers more to a state of extreme anxiety or suffering rather than the commotion described. Choice C, 'Suffering,' is not the best fit as the word 'tumult' in this context does not specifically imply suffering, but rather a noisy and chaotic situation.

Correct Answer: D

Rationale: The correct answer is D, 'Bond.' In this context, 'rapport' refers to a close and harmonious relationship or connection between people. The sentence suggests that a bond or connection developed quickly between the nurses and teenage aides. Choices A, B, and C are incorrect because 'rapport' does not relate to performance, narrative, or manner in this context.

Correct Answer: A

Rationale: The correct answer is A: 'Makes a suggestion about.' The phrase 'suggests that' indicates that the study is proposing or indicating the possibility that vaping may have certain effects on cigarette smoking. It is not stating a fact or providing evidence, but rather making a suggestion or recommendation about the relationship between vaping and cigarette smoking. Choices B, C, and D are incorrect because the phrase 'suggests that' does not provide evidence, hint at an idea, or promote a plan, but rather presents a suggestion or possibility.

Correct Answer: A

Rationale: In this context, 'undulate' means to move in a smooth, wave-like motion. An undulation of muscles is a subtle, continuous rippling or rolling movement, making 'ripple' the most appropriate synonym in this sentence. 'Shake' (Choice B) is incorrect as it implies a more abrupt and irregular movement. 'Flatten' (Choice C) and 'Unknot' (Choice D) are unrelated to the smooth, wave-like motion described in the sentence.