The muscle weakness of myasthenia gravis results from
A) inability of the muscle fiber to produce ATP.
B) insufficient acetylcholine release from presynaptic vesicles.
C) the motor neuron action potential being too small to shock the muscle fibers.
D) loss of acetylcholine receptors in the end- plate membrane.
E) excessive acetylcholinesterase that destroys the neurotransmitter.
Answer: D