There are three regulatory molecules that stimulate acid secretion (acetylcholine, histamine, gastrin)
Vagal activation causes secretion of acetylcholine.
The main constituent of gastric acid is hydrochloric acid which is produced by parietal cells Gastric acid production is regulated by both the autonomic nervous system and several hormones.
The parasympathetic nervous system, via the vagus nerve, and the hormone gastrin stimulate the parietal cell to produce gastric acid, both directly acting on parietal cells and indirectly, through the stimulation of the secretion of the hormone histamine from enterochromaffine-like cells (ECL).
Vasoactive intestinal peptide, cholecystokinin, and secretin all inhibit production.
Answer : (d)