Concept: This question tests your understanding of the basic structural components that constitute a synapse, the junction between two neurons or between a neuron and an effector cell.

Why (D) is correct: A synapse is a specialized junction that allows a neuron to pass an electrical or chemical signal to another neuron or to an effector cell. It is structurally composed of three main parts: the pre-synaptic membrane (from the axon terminal of the transmitting neuron), the post-synaptic membrane (from the dendrite or cell body of the receiving neuron), and the synaptic cleft (the microscopic gap between these two membranes). All three components are essential for synaptic transmission.

Why other options are wrong:

• (A) pre-synaptic membrane alone does not form a complete synapse.
• (B) post-synaptic membrane alone does not form a complete synapse.
• (C) synaptic cleft alone does not form a complete synapse.

NEET Tip: Remember that the synaptic cleft is the space where neurotransmitters are released and diffuse to bind to receptors on the post-synaptic membrane, facilitating signal transmission.

Correct Answer: (D)