Concept: This question tests your understanding of the structural and functional differences between myelinated and non-myelinated axons, which are crucial for nerve impulse conduction.

Why (A) is correct: Myelinated axons are covered by a myelin sheath, which acts as an electrical insulator. This sheath is interrupted by gaps called Nodes of Ranvier. Due to this insulation, the nerve impulse 'jumps' from one node to the next, a process called saltatory conduction, making it much faster. Non-myelinated axons lack this myelin sheath, so the impulse propagates continuously along the entire length of the axon, which is slower.

Why other options are wrong: The specific differences in structure and conduction speed are accurately captured in option A. Other options would contain inaccuracies regarding the presence of myelin, Nodes of Ranvier, or the speed of conduction.

Common Mistake: Students often confuse the role of the myelin sheath, sometimes thinking it slows down conduction, when in fact it significantly speeds it up.

NEET Tip / Mnemonic: Think of myelin as a 'speed booster' for nerve impulses. Myelinated = Much faster.

Correct Answer: (A)