Please choose the correct ending to complete the given sentence: Health: [header] How to treat heartburn [title] Learn how stomach acid normally helps in digestion. [step] Acidic liquid is naturally-produced by the stomach to help your body break down and digest food. The acid is secreted by parietal cells in the the stomach in response to stimulation by gastrin.

Ending1: The gastrins build up in the stomach and inhibit the taste of food. When the acid is activated, the gastrins release an acid into the blood stream resulting in an increased or decreased level of the acid. Ending2: This protein acts to break down carbohydrates, which causes poor gut health. The acid then is then applied directly to your dry bile glands. Ending3: It also kills pathogens in your gastrointestinal tract which can prevent infection. There's no way to completely eliminate stomach acid, nor would you want to. Ending4: The esophagus, located on the side of the stomach, secretes the acid. Stool is acidic in the stomach, especially in the intestines.

Answer format: ending1/ending2/ending3/ending4