Which of the following statements describes an advantage of the catechol ortho-methyltransferase (COMT) inhibitors during the treatment of Parkinson's disease?
a. They have a shorter duration of action.
b. They cause less gastrointestinal distress.
c. They have a slower onset than traditional Parkinson's disease drugs.
d. They are associated with fewer "wearing-off" effects and have prolonged therapeutic benefits.
