(A) Less than 7
Gastric glands release hydrochloric acid (HCl) during digestion, making the gastric juice acidic. Any acidic solution has a pH less than 7.
The passage states that gastric glands release hydrochloric acid, which creates an acidic medium for pepsin to act. Acidic solutions always have pH < 7. Option (D) — pH = 0 — is incorrect as pure HCl is pH 0 but gastric juice is dilute acid, not pure acid. Examiners expect you to simply select (A) and may ask for a one-line justification.