Concept: This question tests your knowledge of the basic anatomy and composition of the spinal cord, specifically distinguishing between grey and white matter.

Why (A) is correct: The grey matter of the spinal cord is primarily composed of neuronal cell bodies, dendrites, unmyelinated axons, and neuroglia. It is the region where synapses occur and information processing takes place.

Why other options are wrong:

• (B) myelin: Myelin is the fatty sheath that insulates axons and is primarily found in the white matter, giving it its characteristic white appearance.
• (C) Both (a) and (b): This is incorrect because myelin is characteristic of white matter, not grey matter.
• (D) Purkinje cell: Purkinje cells are a specific type of large, branched neuron found exclusively in the cerebellum, not the spinal cord.

Common Mistake: Students often confuse the components of grey and white matter, especially regarding the presence of myelin.

NEET Tip / Mnemonic: Remember 'Grey for Ganglia, White for Wires'. Grey matter contains cell bodies (like a ganglion), while white matter contains myelinated axons (like insulated wires).

Correct Answer: (A)