Coordination and response — practice question

The diagram illustrates a synapse within a reflex arc. Identify the two neurones and state the direction in which the neurotransmitter moves.

• Aneurone P: motor, neurone Q: relay, direction: P → Q
• Bneurone P: motor, neurone Q: sensory, direction: P → Q
• Cneurone P: relay, neurone Q: motor, direction: Q → P
• Dneurone P: relay, neurone Q: sensory, direction: Q → P