Final answer:
The occult blood test detects hidden blood in feces and is used for early detection of gastrointestinal issues including colorectal cancer.
Step-by-step explanation:
An occult blood test is a medical test that is used to detect blood that is not visible to the eye in a human body specimen. The correct answer to the question is a) Feces (stool). An occult blood test is primarily performed on a stool sample to check for blood in the feces, which can be an early sign of colitis, polyps, hemorrhoids, or colorectal cancer. It is important for the early detection of conditions that may not show overt symptoms. This test is used to detect the presence of hidden blood in the stool, which can be an indication of various gastrointestinal conditions such as ulcers, polyps, colorectal cancer, or inflammatory bowel disease. It is a simple and non-invasive procedure that is commonly recommended for individuals experiencing persistent gastrointestinal symptoms.