Select the correct answer explaining why the stomach does not digest itself. Select one: a. The stomach wall lacks proteins so enzymes won't attack it. b. The stomach lining is too tough to be digested. c. The digestive enzymes in the stomach aren't efficient enough. d. The stomach is protected by HCl. e. The stomach wall is protected by large amounts of mucus.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.