The human stomach is an extremely acidic environment. This allows the stomach to break down food so nutrients can be absorbed as it moves through the digestive system. Stomach acid is more acidic than lemon juice, which has a pH of around 2.0.

Which could possibly be the pH of gastric acid?

3.5
7
1.2
9.1

When can a theory be modified if a new type of technology allows for new observations that raise new questions? a-immediately, while the questions about the theory are being asked b-after new hypotheses related to the theory are tested in experiments c-only after the new observations disprove all parts of the theory d-while scientists begin to think about how the theory could improve