When Reviewing Pharmacology Terms for a Group of Newly Graduated

When reviewing pharmacology terms for a group of newly graduated nurses, the nurse explains that a drug's half-life is the time it takes for

A) the drug to cause half of its therapeutic response.
B) one half of the original amount of a drug to reach the target cells.
C) one half of the original amount of a drug to be removed from the body.
D) one half of the original amount of a drug to be absorbed into the circulation.