**Core Concept**
In cases of acute head injury, patients may require urgent surgical intervention to relieve intracranial pressure. This is particularly true in cases where there is a significant increase in intracranial pressure, leading to herniation of the brain tissue. The decision to perform a craniotomy (cranial decompression) is often made in emergency situations.

**Why the Correct Answer is Right**
The correct answer involves the use of a "temporary" external ventricular drain (EVD) as a bridge to definitive surgical intervention. EVD placement allows for the diversion of cerebrospinal fluid (CSF) from the ventricular system, thereby reducing intracranial pressure. This procedure can be performed quickly and is often used in emergency situations where time is of the essence. The EVD can also provide valuable information regarding the patient's intracranial pressure and CSF dynamics.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the need for urgent surgical intervention in a head-injured patient with no relatives. Waiting for relatives to arrive may compromise the patient's chances of survival.

**Option B:** This option is incorrect because it suggests performing a craniotomy without first attempting to reduce intracranial pressure with other means, such as EVD placement.

**Option C:** This option is incorrect because it implies that a craniotomy is the only option for reducing intracranial pressure, which is not the case. Other interventions, such as EVD placement, may be more appropriate in certain situations.

**Clinical Pearl / High-Yield Fact**
In cases of head injury, the "first hour" is crucial in determining patient outcomes. Early recognition and treatment of increased intracranial pressure can significantly improve patient outcomes.

**Correct Answer: B. Perform a craniotomy if there is no time to place an EVD.**