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: C

Rationale: The word 'contemptuous' means showing disdain or scorn for something or someone. Therefore, the word 'scornful' is the most closely related synonym to 'contemptuous' in this list. 'Sympathetic' means showing compassion, 'exhausted' means very tired, and 'insensitive' means lacking empathy. These options do not convey the same meaning as 'contemptuous'.

Correct Answer: A

Rationale: The best description of the verb emit is 'to discharge.' Emit means to produce and release something such as a sound, odor, or substance. Discharge is synonymous with emit in this context as it conveys the idea of releasing or sending out something, which aligns with the meaning of emit. Choices B, C, and D are incorrect. 'To exclude' means to deny access or prevent from entering, which is not the same as emit. 'To dismiss' means to remove from consideration or to let go, which is different from emitting. 'To moderate' means to make or become less extreme, intense, or severe, which is not the same as emitting or releasing something.

Correct Answer: D

Rationale: If a lump under the skin is palpable, it means that it can be felt or touched. Palpable lumps can be detected by touch, which can lead to further evaluation or examination by a healthcare professional to determine the cause and appropriate treatment. The correct answer is 'D' because when a lump is palpable, it means it can be physically felt, indicating its presence under the skin. Choices A, B, and C are incorrect because the palpability of a lump does not automatically indicate malignancy, bursting, or warmth.

Correct Answer: B

Rationale: A mass of tissue formed in the ovary is known as the corpus luteum. The corpus luteum is a temporary endocrine structure involved in the production of progesterone, which is essential for preparing and maintaining the uterus for pregnancy. Choices A, C, and D are incorrect. Corpus delicti refers to the body of a crime, corpus striatum is a part of the brain, and corpus callosum is a structure that connects the two hemispheres of the brain.