Which of the following fluid compartments contains the smallest volume of water?

Correct Answer: A

Rationale: Plasma, part of the extracellular fluid, is the smallest compartment by volume, making up about 5% of total body water.

Correct Answer: B

Rationale: Increased sweating reduces blood volume, triggering aldosterone release, which decreases urinary sodium loss.

Correct Answer: D

Rationale: Lower plasma osmolality inhibits ADH, increasing urine production to excrete excess water.

Correct Answer: C

Rationale: Aldosterone increases sodium reabsorption, leading to hypernatremia.

Correct Answer: D

Rationale: Increased aldosterone secretion enhances potassium excretion to correct hyperkalemia.