**Core Concept**
The cuff used in an Endotracheal tube (ETT) is a crucial component that helps maintain a secure airway by preventing leaks around the tube. The cuff's primary function is to create a seal between the ETT and the tracheal wall, ensuring adequate ventilation and minimizing the risk of aspiration.

**Why the Correct Answer is Right**
The cuff used in ETTs is typically made of a non-compliant material, such as latex or silicone, that can be inflated to create a tight seal around the trachea. When the cuff is inflated, it prevents the escape of carbon dioxide and oxygen, thereby ensuring that the patient receives the correct tidal volume. The cuff also helps to prevent aspiration of gastric contents into the lungs by creating a seal around the tracheal wall.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe the typical material used to make the cuff.
**Option B:** This option is incorrect because it does not describe the primary function of the cuff.
**Option C:** This option is incorrect because it does not accurately describe the type of material used to make the cuff.

**Clinical Pearl / High-Yield Fact**
It is essential to check the cuff's pressure regularly to prevent over-inflation, which can lead to tracheal damage and mucosal ischemia. A pressure of 20-30 cmH2O is generally recommended to ensure an adequate seal without causing harm.

**Correct Answer:** C.