Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface.
The correct option is D.
Parietal cells are the epithelial cells which secrete hydrochloric acid and intrinsic factors. The cells are located in the gastric glands which are found in the linings of the walls of the stomach. The hydrochloric acid produced by the parietal cells helps in the conversion of the enzyme pepsinogen to pepsin during the digestion process.
