Given that impulses from parasympathetic nerves decrease heart rate, and that the neurotransmitter for parasympathetic postganglionic fibers is acetylcholine (ACh), predict how the following chemicals might affect heart rate.

A) Pilocarpine, a drug that simulates the action of ACh, will decrease heart rate.
B) Pilocarpine, a drug that simulates the action of ACh, will increase heart rate.
C) Pilocarpine, a drug that simulates the action of ACh, will increase heart rate; and atropine, a drug that blocks the action of ACh, will decrease heart rate.
D) Atropine, a drug that blocks the action of ACh, will decrease heart rate.