Which of the following cells increase acid in the stomach? (Select all that apply)

Choice A reason: Enterochromaffin-like (ECL) cells release histamine, which stimulates parietal cells to secrete hydrochloric acid via H2 receptors. This increases gastric acid production, critical for digestion, and is a key component in the acid secretion pathway, making this a correct choice for acid-increasing cells. Choice B reason: Beta cells, located in the pancreas, secrete insulin to regulate glucose, not gastric acid. They have no role in stomach acid production or regulation, which is controlled by gastric cells like parietal or G cells, making this choice incorrect. Choice C reason: Parietal cells directly secrete hydrochloric acid into the stomach lumen via the H+/K+-ATPase pump, significantly increasing gastric acidity for digestion. Activated by histamine, gastrin, and acetylcholine, they are central to acid production, making this a correct choice for the question. Choice D reason: Mucus cells secrete protective mucus to shield the stomach lining from acid and pepsin, not acid itself. They reduce damage from acidity but don’t contribute to its production, making this choice incorrect for cells that increase stomach acid. Choice E reason: G cells secrete gastrin, a hormone that stimulates parietal cells to produce hydrochloric acid. Gastrin enhances acid secretion indirectly by activating parietal cells and ECL cells, playing a key role in gastric acid regulation, making this a correct choice.