During synaptic transmission:a. receptors that bind neurotransmitters trigger a change in postsynaptic membrane potential. b. neurotransmitter-filled vesicles fuse with the postsynaptic membrane. c. neurotransmitters are absorbed by the postsynaptic membrane. d. voltage-gated calcium channels open in the postsynaptic membrane.

a. receptors that bind neurotransmitters trigger a change in postsynaptic membrane potential.

Explanation: Synaptic transmission is the communication between a neuron with another neuron. When the electrical impulse reaches the synaptic vesicles, they release their contents of neurotransmitters.

The neurotransmitters released into the synaptic cleft binds with the postsynaptic receptors and activates a receptor in the postsynaptic membrane. The binding of neurotransmitter results to the opening of channels in the neuron. Also, binding of neurotransmitters may influence the postsynaptic neuron in either an inhibitory or excitory way.

The binding of neurotransmitters to receptors in the postsynaptic neuron can trigger either short term changes or long-term changes.

A change in postsynaptic membrane potential.By causing opening of ligand gated  Sodium-channels (on the membrane of postsynaptic neuron) which cause sodium influx, reversal of charges, and therefore depolarization.

If the  stimulus is strong enough more sodium channels opens,and therefore action potential is generated. if the potential is sustained to the threshold levels  action potential is propagated along the postsynaptic nerve fibre as inhibitory or excitatory  postsynaptic potential.( IPSP / EPSP,).

Thus changing the potential  from the Pre- synaptic potential that crosses the synaptic cleft to Postsynaptic potential in the membrane of  postsynaptic nerve fiber.

the correct answer is d