As the patient's digoxin level reaches a therapeutic range, how does the heart rate respond?

a. It will decrease to normal.
b. It will increase to normal.
c. It will initially increase, then decrease.
d. It will stay the same.

c. It will initially increase, then decrease.

As the patient's digoxin level reaches a therapeutic range, the heart rate initially increases, then gradually decreases. Therefore, the correct answer is option c. It will initially increase, then decrease.