**Core Concept**
The Sellick maneuver, also known as cricoid pressure, is a technique used during endotracheal intubation to prevent the regurgitation of gastric contents into the airway. This is particularly important in patients at risk of aspiration, such as those with a full stomach or those undergoing emergency surgery.

**Why the Correct Answer is Right**
The Sellick maneuver works by applying pressure to the cricoid cartilage, which is located below the vocal cords in the larynx. This pressure compresses the esophagus, preventing the upward movement of gastric contents into the pharynx and thereby reducing the risk of aspiration. The esophagus is compressed because the cricoid cartilage surrounds it, effectively pinching it shut. This is a critical step in ensuring patient safety during anesthesia.

**Why Each Wrong Option is Incorrect**
**Option A:** Alveolar collapse is not directly related to the Sellick maneuver, which is focused on preventing aspiration of gastric contents, not lung collapse.

**Option B:** Hypertension is not prevented by the Sellick maneuver, as it is not a technique used to manage blood pressure.

**Option D:** Bradycardia, or a slow heart rate, is not a complication associated with the Sellick maneuver. In fact, the maneuver is typically used in conjunction with other anesthesia techniques to ensure patient safety, not to cause cardiac complications.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the Sellick maneuver should only be applied after the patient has been anesthetized, as the pressure can cause respiratory distress if applied too early. Additionally, the maneuver should be released before extubation to prevent esophageal injury.

**✓ Correct Answer: C. Aspiration of Gastric content**