Which of the Following Is a Criterion for Identifying a Neurotransmitter

Multiple Choice

Which of the following is a criterion for identifying a neurotransmitter?

A) The transmitter must be synthesized in the neuron or otherwise be present in it.
B) When the neuron is active, the transmitter must be released and must produce a response in some target.
C) A mechanism must exist for removing the transmitter from its site of action after its work is done.
D) All of the above are criteria for identifying a neurotransmitter.