Which test is used to identify the presence of occult blood in stool?

Correct option is A

The Benzidine test is used to detect the presence of occult (hidden) blood in the stool. It involves the use of benzidine reagent, which turns blue when it reacts with the heme in blood.
Explanation of options: (a) ✔ Correct. The Benzidine test is specifically used to detect occult blood in the stool. (b) ✘ Incorrect. Duke’s test is used to measure bleeding time, not for detecting occult blood in stool. (c) ✘ Incorrect. Ivy test is also used to measure bleeding time. (d) ✘ Incorrect. Benedict test is used to detect reducing sugars in urine, not for occult blood.