Refer to the Figure Shown

Refer to the figure shown.
In order to function effectively as an oscillatory network, the half-center model depicted in the figure must

A) include a cell that depolarizes spontaneously.
B) involve a mechanism for the activated neuron to stop signaling.
C) involve a mechanism for one of the neurons to start signaling first.
D) includes both excitatory and inhibitory synapses between the two neurons.