Final answer:
Acetylcholine is classified as a biogenic amine similar to histamine, and it plays a key role at the neuromuscular junction and in the autonomic nervous system.
Step-by-step explanation:
Acetylcholine is in the same class of neurotransmitters as histamine, because both are classified as biogenic amines. Biogenic amines are derived from amino acids and are characterized by containing amino groups; they do not have carboxyl groups and so are not classified as amino acids. Acetylcholine is specifically used at the neuromuscular junction to activate muscles and is also involved in the autonomic nervous system. It is different from neurotransmitters like serotonin and dopamine, which are biogenic amines as well but belong to different systems within the body. Therefore, the correct answer to the question would be 'b. histamine'.