**Core Concept**
Severe maxillofacial trauma can lead to significant airway compromise, necessitating immediate intervention to secure a patent airway, maintain oxygenation, and prevent further complications.

**Why the Correct Answer is Right**
In cases of severe maxillofacial trauma, the patient is at risk of airway obstruction due to blood, debris, or swelling in the airway. The patient's SpO2 of 80% indicates significant hypoxemia, further emphasizing the need for immediate intervention. The correct answer prioritizes securing the airway using endotracheal intubation, which is a critical step in managing severe trauma patients.

**Why Each Wrong Option is Incorrect**
* **Option A:** Administering oxygen alone is insufficient in this scenario, as the patient's airway is compromised and requires direct visualization and intervention.
* **Option B:** Administering fluids to manage hypotension is not the immediate priority in this case, as the patient's airway needs to be secured first.
* **Option D:** Performing a rapid sequence induction (RSI) without considering the patient's airway status can lead to complications, such as aspiration or airway obstruction.

**Clinical Pearl / High-Yield Fact**
In trauma patients with signs of airway compromise, always prioritize securing the airway using endotracheal intubation before addressing other issues, such as hypotension or hypoxemia.

**Correct Answer: C. Secure the airway with endotracheal intubation.**