Correct Answer: B

Rationale: The correct answer is B: 'Produced within the body.' Endogenous refers to substances or processes that originate or are produced within an organism or system. Choices A, C, and D are incorrect. Choice A, 'Produced outside the body,' is the opposite of endogenous. Choice C, 'Taken from an external source,' describes exogenous rather than endogenous. Choice D, 'Linked to environmental factors,' is not a direct definition of endogenous.

Correct Answer: A

Rationale: The correct preposition to use after 'within 24 hours' in this context is 'of.' Therefore, the tuberculin skin test should be read within 24 hours of administration. The other choices ('before,' 'after,' 'during') do not correctly convey the relationship between the timing of reading the test and the administration.

Correct Answer: A

Rationale: The correct answer is A: 'Empty.' Vacuous means lacking intelligence, empty-headed, or devoid of substance. Choice B, 'Full,' is incorrect as it is the opposite of vacuous. Choice C, 'Dense,' means closely compacted or stupid, not vacuous. Choice D, 'Bright,' means giving out or reflecting a lot of light, not vacuous.

Correct Answer: B

Rationale: The correct answer is B, 'Wide open'. Gaping refers to something being wide open, not partially closed (choice A), narrow (choice C), or sealed (choice D). In the context of the question, 'Gaping' describes something that is open widely.

Correct Answer: B

Rationale: The correct answer is B: 'Sluggish.' Torpid means being slow or inactive. Choice A, 'Energetic,' is the opposite of torpid. Choice C, 'Fast,' is not synonymous with torpid as it refers to quickness rather than sluggishness. Choice D, 'Slow,' is somewhat related to torpid but does not fully capture the inactive aspect of the term.