Final answer:
Caffeine, nicotine, and alcohol affect synaptic activity by interfering with neurotransmitter reuptake.
Step-by-step explanation:
Caffeine, nicotine, and alcohol all have effects on A. synaptic activity.
Once neurotransmission has occurred, the neurotransmitter must be removed from the synaptic cleft so the postsynaptic membrane can "reset" and be ready to receive another signal.
This can be accomplished by reuptake, where the neurotransmitter is recycled by the presynaptic neuron. Caffeine, nicotine, and alcohol can interfere with this process, affecting synaptic activity.