Final answer:
Gastric juice secretion is stimulated by excitatory impulses from the vagus nerve, which is a part of the parasympathetic nervous system responsible for the rest-and-digest response.
Step-by-step explanation:
Gastric juice secretion is stimulated by excitatory impulses from the vagus nerve. The autonomic nervous system controls extrinsic innervations of the alimentary canal, with sympathetic nerves generally inhibiting GI secretion and motility, and parasympathetic nerves doing the opposite. The vagus nerve, which is part of the parasympathetic nervous system, activates the rest-and-digest response, therefore increasing gastric secretion and motility. This coincides with the cephalic phase of gastric secretion, which begins when food is smelled or thought about, hence stimulating cells in the stomach to begin secreting digestive juices.
In the context of gastric secretion, the correct answer to the student's question would be option (b) Excitatory, vagus.