When you step on a tack, excitation of sensory afferents leads to excitation of motor neurons innervating one set of muscles and inhibition of motor neurons innervating another set of muscles. The stimulus produces opposite responses in different motor neurons because

A) motor neurons innervating different muscles have different receptors.
B) the afferent neuron releases different neurotransmitters at different synapses.
C) the sensory afferents transmit both excitatory and inhibitory action potentials that are sent to different motor neurons.
D) the signals reach some motor neurons via excitatory interneurons but they reach other motor neurons via inhibitory interneurons.