In the Intestine, the Smooth Muscle Cell's

In the intestine, the smooth muscle cell's

A) contraction requires an action potential but its force is graded by the extent of neurotransmitter released.
B) force of contraction is graded by the extent of depolarization for slow waves until an action potential is generated.
C) contraction requires an action potential and its force is therefore graded by the frequency of action potentials.
D) force of contraction is graded by the extent of depolarization for slow waves whether an action potential is generated or not.
E) contraction is stimulated by motor neurons.