Neurons communicate with each other through
a. synaptic transmission
b. neural receptors
c. postsynaptic signals
d. neural impulses

The answer is a. synaptic transmission.
Synaptic transmission is a process of communication between two neurons. The communication occurs through a synapse, a structure that enables a neuron to send a signal to another one. The communication between two neurons happens as follows: the presynaptic neuron releases signaling molecules - neurotransmitters - which pass through synapses and bind to the receptors on another neuron. 

The diaphragm is what i think ur talking about