67. The following events are steps of neural transmission at a chemical synapse. Please choose the correct sequence of events. (1) Neurotransmitter binds with receptors associated with the postsynaptic membrane. (2) Calcium ions rush into neuron's cytoplasm. (3) The ligand-gated ion channels open. (4) An action potential depolarizes the membrane of the axon terminal. (5) The synaptic vesicles release neurotransmitter into the synaptic cleft. (A) 1 → 2 → 3 → 4 → 5 (B) 2 → 3 → 5 → 4 → 1 (C) 3 → 2 → 5 → 1 → 4 (D) 4 → 2 → 5 → 1 → 3 (E) 5 → 1 → 2 → 3 → 4