Concept: This question tests your understanding of the structure and functions of the spinal cord, a vital part of the central nervous system.

Why (D) is correct: The spinal cord performs all the functions listed. It acts as a minor coordinating centre for reflexes, meaning it can process some information and initiate responses without direct input from the brain. It serves as the primary conduit, connecting the peripheral neural system (nerves extending throughout the body) to the brain, allowing for the transmission of sensory information to the brain and motor commands from the brain to the body. Therefore, it acts as the crucial link between the brain and the nerves stretching throughout the body.

Why other options are wrong:

(A) is incorrect because while true, it's not the only function. The spinal cord is indeed a minor coordinating center for reflexes.

(B) is incorrect because while true, it's not the only function. It connects the PNS to the brain for information transfer.

(C) is incorrect because while true, it's not the only function. It acts as the link between the brain and peripheral nerves.

NEET Tip: Remember that the spinal cord is not just a relay station; it has its own processing capabilities, especially for reflex actions.

Correct Answer: (D)