Amylase digests starch most effectively without pH interference

Steps:

• Amylase enzyme breaks down starch in agar into simpler sugars, creating a starch-free zone.
• Hydrochloric acid lowers pH, potentially denaturing enzymes like amylase.
• Gastric protease targets proteins, not carbohydrates like starch.
• Compare zones: largest clearance indicates most starch digestion.

Why A is correct:

• Amylase specifically catalyzes starch hydrolysis via glycosidic bond cleavage, optimal at neutral pH.

Why the others are wrong:

• B: Acid denatures amylase, inhibiting starch breakdown.
• C: Protease digests proteins, leaving starch intact.
• D: Protease ineffective on starch; acid provides no benefit for carb digestion.

Final answer: A