Review: stimulus, neurons, and nervous system

Question one:
A stimulus of 70 millivolts (mV) applied to dendrite end causes an impulse to travel along the neuron. A stimulus of 50 mV produces a similar action. This demonstrates that:
A. Depolarization is not dependent upon the strength of the stimulus
B. The greater the voltage difference, the stronger the neural response
C. 50 mV is the threshold level
D. Above the threshold value, the neural response is constant

(I think its B, but I could be wrong?)

Question two:
Cells that nourish, remove wastes, and defend neurons agaisnt infections are:

A. Parasympathetic cells
B. Cell bodies
C. Sympathetic cells
D. Glial cells

(I think its B, cell bodies?)