Why is the pressure of a firm handshake experienced as more intense than the pressure of a feather resting lightly in your hand?

a. The greater pressure of the firm handshake causes the sensory receptors in the skin to trigger faster neural impulses.
b. The greater pressure of the firm handshake causes the sensory receptors in the skin to trigger more intense neural impulses.
c. The greater pressure of the firm handshake causes the sensory receptors in the skin to trigger more frequent neural impulses.
d. All of the above.
e. None of the above.