Name the system that contains three neurons

Consider a system that contains three neurons in a culture dish bathed in normal physiological saline.  All three neurons are healthy.  Neuron A synapses onto Neuron B. Neuron B synapses onto Neuron C.  Neuron A has GABA in its synaptic vesicles. Neuron B has glycine in its synaptic vesicles.  The only ligand-gated receptors in Neuron A are AMPA channels.  The only ligand-gated receptors in the plasma membrane of Neuron B are GABA_B receptors.  The only ligand-gated receptors in the plasma membrane of Neuron C are glycine receptors.  All 3 neurons have no other ligand-gated receptors in their plasma membranes.  All 3 neurons have a sodium equilibrium potential of +60 millivolts. All 3 neurons have a potassium equilibrium potential of -86 millivolts.  All 3 neurons a chloride equilibrium potential of -20 millivolts. The threshold for an action potential in all 3 neurons is -55 millivolts.  At 1:55 AM, glutamate is added to the physiological saline.  At 2:00 AM, the action potential firing rate of each neuron is 100 Hz.  Which of the following will lead to an increase in Neuron C's action potential firing rate?

A. At 2:01 AM, GABA is added to the bath.

B. At 2:01 AM, CNQX is added to the bath.

C. At 2:01 AM, glycine is added to the bath.