A diagram showing axon terminal and synapseis given. Identify correctly at least two of A-D.

A

C-Neurotransmitter
$$D-Ca^{++}$$

B

A-Receptor
C-Synaptic vesicles

C

B-Synaptic vesicles
$$D-K^{+}$$

D

A-Neurotransmitter
B-Synaptic cleft