Concept: This question tests your understanding of the basic structure of a neuron, specifically the location of the synaptic knob.

Why (A) is correct: The synaptic knob (also known as the axon terminal or terminal bouton) is indeed a bulb-like structure located at the very end of the axon terminal. It contains neurotransmitters packaged in vesicles, ready for release into the synaptic cleft to transmit signals to the next neuron or effector cell.

Why other options are wrong:

• (B) at the node of Ranvier: Nodes of Ranvier are gaps in the myelin sheath along the axon, crucial for saltatory conduction, not synaptic transmission.
• (C) in the cell body: The cell body (soma) contains the nucleus and most organelles, but not the synaptic knob.
• (D) at the end of dendrites: Dendrites receive signals and typically do not have synaptic knobs; they have dendritic spines or receptors.

Common Mistake: Students sometimes confuse the different parts of a neuron and their functions, especially the axon terminal with dendrites or the cell body.

NEET Tip / Mnemonic: Think of the axon as the 'transmitter' and the synaptic knob as the 'sending station' at its very end.

Correct Answer: (A)