Which of the following statement is true?:

• A. The intrinsic factors is secreted by the parietal cells of the gastric mucosa.
• B. The gastric juice can t digest the gastric mucosa because the cell membranes contain a pepsin activator.
• C. The stomach normally absorbs about 30% of the ingested food.
• D. The secretion of the gastric juice is associated with increased H in the blood.