A college student wakes up several times at night to urinate after drinking wine because

• A. transient suppression of vasopressin by alcohol leads to decreased aquaporin insertion and increased water excretion.
• B. alcohol functions as a nonreabsorbable solute in the nephron, creating an osmotic gradient for water loss.
• C. alcohol irreversibly impairs thick ascending limb countercurrent multiplication, reducing concentrating ability after a single exposure.
• D. alcohol enhances insensible fluid losses (sweating, respiration), prompting compensatory nocturnal diuresis.

Answer: (A)