**Core Concept**
The Sengstaken-Blakemore tube is a medical device used to control bleeding from esophageal or gastric varices. The tube has a balloon that can be inflated to apply pressure to the bleeding site. The pressure required to stop bleeding is critical to prevent further complications.

**Why the Correct Answer is Right**
The Sengstaken-Blakemore tube must maintain a pressure of 40-60 mmHg to stop bleeding from varices. This is because the bleeding varices have a fragile blood vessel wall that can be easily compressed by the applied pressure. The pressure range of 40-60 mmHg is sufficient to compress the varices without causing further damage to the surrounding tissues. The esophageal balloon must be inflated to a pressure of 40-60 mmHg and the gastric balloon to 60-80 mmHg to achieve this effect.

**Why Each Wrong Option is Incorrect**
**Option A:** 20 mmHg is too low to effectively compress the bleeding varices and may not stop the bleeding.
**Option B:** 100 mmHg is too high and may cause further damage to the surrounding tissues, leading to complications such as esophageal rupture.
**Option C:** 10 mmHg is even lower than option A and is unlikely to stop bleeding from varices.

**Clinical Pearl / High-Yield Fact**
Remember the Sengstaken-Blakemore tube inflation pressures: esophageal balloon 40-60 mmHg and gastric balloon 60-80 mmHg to effectively control bleeding from varices.

**Correct Answer:** C. 40-60 mmHg