**Core Concept**
In emergency situations, the principle of necessity prevails over the principle of consent. This means that doctors can perform life-saving interventions without obtaining explicit consent from the patient or their representatives, as long as the intervention is deemed necessary to prevent harm or death.

**Why the Correct Answer is Right**
The correct answer is based on the doctrine of implied consent, which holds that patients implicitly consent to treatment in emergency situations where their life is at risk. This doctrine is rooted in the idea that patients who are unable to give consent themselves have a right to receive necessary medical treatment. In the case of a head injury victim who is unconscious, the doctor must act quickly to prevent further harm or death. Operating without consent is justified in this scenario as it is the only way to ensure the patient receives the necessary medical attention.

**Why Each Wrong Option is Incorrect**
**Option A:** Not operating at all would be a violation of the doctor's duty to act in the patient's best interest and could result in further harm or death.

**Option B:** Obtaining consent from the police is not relevant in this scenario, as the police do not have the authority to grant consent for medical treatment.

**Option D:** Obtaining consent from the magistrate is not practical in emergency situations, where every minute counts, and the patient's life is at risk.

**Clinical Pearl / High-Yield Fact**
In emergency situations, doctors must balance the need for consent with the need to act quickly to prevent harm or death. This is often referred to as the "implied consent" doctrine, which holds that patients implicitly consent to treatment in emergency situations where their life is at risk.

✓ Correct Answer: C. Operate without consent