Question: Which of the following best describes the term \'bioavailability\'?

Options:

1. The rate of drug metabolism
2. The extent and rate at which the active ingredient is absorbed
3. The elimination half-life of a drug
4. The distribution of a drug in body tissues

Correct Answer: The extent and rate at which the active ingredient is absorbed

Solution:

Bioavailability refers to the extent and rate at which the active ingredient or active moiety is absorbed and becomes available at the site of action.