**Core Concept**
Aspiration pneumonia occurs when oral secretions or gastric contents enter the lower respiratory tract. Prevention relies on maintaining a secure airway and minimizing the risk of gastric contents entering the trachea during anesthesia or intubation.

**Why the Correct Answer is Right**
A cuffed endotracheal tube creates a seal between the trachea and the surrounding tissues, preventing gastric contents from entering the lower airway. This is especially critical during anesthesia when the patient is unconscious and protective reflexes are suppressed. The cuff compresses the tracheal wall, ensuring that airway patency is maintained while blocking reflux of stomach contents into the lungs.

**Why Each Wrong Option is Incorrect**
Option B: Inhalational anesthesia does not prevent aspiration; it may even increase risk by causing gastric distension and reducing protective reflexes.
Option C: Increased intra-abdominal pressure can elevate intrathoracic pressure and may worsen ventilation, but it does not prevent aspiration.
Option D: A full stomach increases aspiration risk, not prevents it — it is a contraindication, not a preventive measure.

**Clinical Pearl / High-Yield Fact**
Always use a cuffed endotracheal tube in patients at risk of aspiration. The cuff pressure should be maintained at 20–25 cmH₂O to ensure seal without causing tracheal injury.

✓ Correct Answer: A. Cuffed endotracheal tube