**Core Concept**
The immediate management of a patient with severe maxillofacial trauma involves stabilizing the airway, breathing, and circulation (ABC) to prevent further complications. In this scenario, the patient's SpO2 is critically low, indicating severe respiratory compromise.

**Why the Correct Answer is Right**
The patient's severe maxillofacial trauma may have caused an obstruction or fracture of the airway, leading to hypoxia. The first step in managing this patient is to secure the airway using an endotracheal tube (ETT) or a cricothyrotomy, if necessary. This is crucial to prevent further hypoxia and subsequent cardiac arrest. The high pulse rate (tachycardia) and low blood pressure (hypotension) are likely compensatory mechanisms due to the severe blood loss or hypovolemia.

**Why Each Wrong Option is Incorrect**
**Option A:** Administering oxygen alone may not be sufficient to address the patient's severe hypoxia, as the airway is likely obstructed or compromised.

**Option B:** The patient's severe maxillofacial trauma and subsequent hypoxia take precedence over the management of tachycardia or hypertension. Addressing the airway and breathing takes priority over the management of circulation.

**Option C:** While maintaining a patent airway is crucial, the patient's severe hypoxia indicates a more immediate need for securing the airway using an ETT or cricothyrotomy, rather than simply maintaining a patent airway.

**Option D:** The patient's severe maxillofacial trauma and subsequent hypoxia take precedence over the management of pain, which can be addressed after securing the airway and stabilizing the patient.

**Clinical Pearl / High-Yield Fact**
In cases of severe maxillofacial trauma, always prioritize securing the airway over managing pain or hypertension. A mnemonic to remember is **"Airway first, then Breathing, then Circulation"**.

**Correct Answer: C. Securing the airway using an endotracheal tube (ETT) or cricothyrotomy is the immediate management of choice.**