State one reason why a low pH is important in the stomach.

• A. Kills germs
• B. Increases absorption
• C. Hydrolyzes starch
• D. Neutralizes enzymes

Answer: (A)

Low pH in the stomach serves as a powerful barrier against ingested microbes. The highly acidic environment created by hydrochloric acid kills or deactivates many germs, reducing the risk of infection as food passes through the digestive tract. This protective action is the clearest reason why acidity is important. The stomach’s acidity also helps unfold proteins and activates pepsin to begin protein digestion, but since you’re asked for one reason, the germ-killing function is the best-supported explanation. The other options don’t fit because acid isn’t used to increase absorption, it doesn’t primarily hydrolyze starch (that work happens before and in the small intestine), and it doesn’t neutralize enzymes; in fact, acid helps activate certain digestive enzymes like pepsin.