How Fast a Person Can Type or Play the Piano

Multiple Choice

How fast a person can type or play the piano is ultimately limited by the number of impulses a person can send to their finger muscles per second. This in turn is limited by

A) primarily the type of muscle.
B) whether the signal is pain, sound, motor, etc.
C) the magnitude or strength of the nerve impulse.
D) the number of neurons and synapses involved.
E) the speed with which sodium ions can be pumped out of the axon.