**Core Concept**
The cuff pressure in endotracheal intubation with prolonged ventilation should be carefully managed to prevent tracheal mucosal damage and stenosis. The ideal cuff pressure is a balance between ensuring a secure airway seal and minimizing tissue injury.

**Why the Correct Answer is Right**
The optimal cuff pressure is below 25 cmH2O to prevent tracheal damage. Higher cuff pressures can lead to ischemia and necrosis of the tracheal mucosa, increasing the risk of tracheal stenosis. The tracheal mucosa is highly sensitive to pressure, and prolonged exposure to high cuff pressures can cause irreversible damage.

**Why Each Wrong Option is Incorrect**
**Option A:** 30 cmH2O is too high and can cause significant tracheal mucosal damage, increasing the risk of stenosis.
**Option B:** 20 cmH2O is still somewhat high and may lead to some tracheal mucosal ischemia, although it is less likely than with higher pressures.
**Option C:** 35 cmH2O is excessively high and can cause severe tracheal mucosal damage, leading to stenosis and potentially life-threatening airway complications.

**Clinical Pearl / High-Yield Fact**
To minimize tracheal damage, it's essential to regularly check and adjust the cuff pressure in patients with prolonged ventilation, ideally using a pressure gauge or manometer. This can help prevent tracheal stenosis and ensure a secure airway.

**Correct Answer: D. 25 cmH2O**