Refer to the Figure Showing the Knee-Jerk Reflex

Refer to the figure showing the knee-jerk reflex. What is happening at point 2?

A) The motor neuron is firing action potentials to its target muscle, causing contraction.
B) The motor neuron for the antagonistic muscle is not firing action potentials because it is inhibited by an interneuron.
C) The motor neuron for the antagonistic muscle is integrating the sensory information received and is sending it to the central nervous system.
D) The motor neuron for the antagonistic muscle is receiving afferent input and firing action potentials.
E) The sensory neuron is sending signals to the dorsal root of the spinal cord.