The amount of blood lost in GIT to produce a single black stool is approximately
**Core Concept**
The question tests the understanding of gastrointestinal bleeding and its clinical presentation, specifically the amount of blood required to produce a single black stool, also known as melena. This phenomenon is related to the digestion and absorption of blood in the gastrointestinal tract.
**Why the Correct Answer is Right**
To produce melena, blood must be digested and acted upon by gastric and intestinal enzymes, resulting in the formation of melanin-like substances that give the stool its characteristic black color. The process involves the action of gastric acid and enzymes like pepsin, which break down the blood.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the amount of blood needed.
**Option B:** This option overestimates the required amount of blood.
**Option D:** This is also an overestimation of the blood amount necessary for melena.
**Clinical Pearl / High-Yield Fact**
Melena typically results from upper gastrointestinal bleeding, and the amount of blood lost to produce a single black stool is approximately 50-100 mL.
**Correct Answer:** C. 50-100 mL