Pyridostigmine Is Useful in Treating Patients with Myasthenia Gravis Because

Pyridostigmine is useful in treating patients with myasthenia gravis because:

A) it increases the secretion of acetylcholine from cholinergic nerve endings.
B) it binds to nicotinic-muscle receptors and produces the same effects as those of acetylcholine.
C) it causes the irreversible inhibition of acetylcholinesterase, thereby increasing the levels of acetylcholine at the parasympathetic postganglionic nerve endings.
D) it causes the reversible inhibition of acetylcholinesterase, thereby increasing the levels of acetylcholine at the skeletal neuromuscular junction.