In the stomach, gastric acid is secreted by the Parietal cells, Peptic cells, Gastrin secreting cells, Acidic cells

Parietal cells in the stomach secrete roughly two liters of acid a day in the form of hydrochloric acid. The acid in the stomach functions to kill bacteria, and aids digestion by solubilizing food. The acid is also important to establish the optimal pH (between 1.8-3.5) for the function of the digestive enzyme pepsin. So, the correct answer is 'Parietal cells'