Question

as tolerance develops, what happens to the margin of safety?
widens but then levels off
widens
narrows
stays the same

Explanation:

When tolerance develops (e.g., to a drug), the margin of safety (difference between therapeutic & toxic doses) narrows. Higher doses are needed for effect, reducing the gap to toxic levels.

Answer:

C. Narrows (assuming options are labeled A - D as per typical MCQ, with "Narrows" being the correct choice here)