A Postsynaptic Neuron Has Three Presynaptic Inputs-From Neurons X,Y,and Z

Multiple Choice

A postsynaptic neuron has three presynaptic inputs-from neurons X,Y,and Z.Stimulation of neuron X causes the postsynaptic neuron to depolarize by 0.5 mV. When X and Y are stimulated simultaneously,the postsynaptic neuron depolarizes by 1 mV. When X and Z are stimulated simultaneously,however,there is no change in the membrane potential of the postsynaptic neuron.What is most likely true about presynaptic neurons Y and Z?

A) They are both excitatory.
B) They are both inhibitory.
C) Y is excitatory and Z is inhibitory.
D) Z is excitatory and Y is inhibitory.