Correct Answer: D

Rationale: Unruffled means calm and not agitated. The word 'composed' also means calm and collected, making it the correct synonym in this context. 'Concerned' (choice A) means worried or anxious, 'wholesome' (choice B) means promoting health and well-being, and 'tedious' (choice C) means boring or monotonous, making them all incorrect choices.

Correct Answer: B

Rationale: Verified means confirmed or proven to be true. When something is verified, it has been established as factual or accurate through thorough examination or evidence. It is the opposite of belittled, anecdotal, or implicit, as those terms do not convey the sense of confirmation or validation that verified does.

Correct Answer: C

Rationale: In the context of the sentence, the word 'placebo' refers to a substance or treatment that resembles a real medical treatment but has no therapeutic effect. It is used as a standard against which the effects of the experimental drug are compared. A placebo is typically included in a control group in medical research to evaluate the actual effects of the experimental drug. Therefore, in this scenario, the placebo serves as a control to gauge the effectiveness of the experimental drug, making choice C the correct answer. Choices A, B, and D are incorrect because a placebo is not a fallback, substitute, or curative treatment in this context.

Correct Answer: D

Rationale: The abbreviation CDC stands for the Centers for Disease Control and Prevention, which is a well-known public health association in the United States. The CDC is a federal agency under the Department of Health and Human Services, responsible for protecting public health and safety by controlling and preventing disease, injury, and disability. Choices A, B, and C are incorrect as they do not accurately describe what the CDC is known for; it is not an online social network, a test for postgraduate students, or a pharmaceutical company.

Correct Answer: C

Rationale: The correct answer is C, 'Evisceration.' Evisceration specifically refers to the surgical removal of an organ's contents, for example, the removal of abdominal contents during certain surgical procedures. Vivisection (A) involves performing experiments on live animals, amputation (B) is the removal of a limb, and augmentation (D) is the process of increasing the size, value, or quality of something. Therefore, in the context of surgical procedures, evisceration best fits the description of removing an organ's contents.