Final answer:
The effect of neurotransmitters on the subsequent neuron depends on receptor type; neurotransmitters may either excite or inhibit the postsynaptic neuron.
Step-by-step explanation:
The effect of neurotransmitters from one neuron on the next neuron can either excite or inhibit it, depending on the types of receptors present in the postsynaptic neuron. When neurotransmitters bind to excitatory receptors, they tend to depolarize the target cell, making it more likely to fire an action potential. In contrast, neurotransmitters that bind to inhibitory receptors tend to hyperpolarize the target cell, making it less likely to fire an action potential.
Some neurotransmitters like acetylcholine can have varied effects based on the receptor subtype they bind to. For example, acetylcholine can induce depolarization when it binds to nicotinic receptors, which are cation channels, but its effect might differ when binding to muscarinic receptors. Therefore, the answer to the student's question is d. They may excite or inhibit it.