**Core Concept**
Diffuse axonal injury (DAI) is a type of traumatic brain injury characterized by widespread damage to axons throughout the brain, often resulting from severe acceleration-deceleration forces. This condition typically presents with minimal or no initial symptoms, but can lead to significant neurological deficits and even death.

**Why the Correct Answer is Right**
The patient's presentation of unconsciousness with external injuries, combined with the CT findings of compressed basal cisterns and multiple small hemorrhages, is suggestive of DAI. In DAI, the brain's axons are damaged due to shear stress, causing microhemorrhages and edema. The absence of midline shift on the CT scan rules out mass effect from a large hemorrhage or tumor, making DAI a more likely diagnosis. The presence of compressed basal cisterns indicates increased intracranial pressure and cerebral edema, which are common features of DAI.

**Why Each Wrong Option is Incorrect**

**Option A:** Brain contusion typically presents with a focal area of injury, often with a visible lesion on CT scan, which is not described in this case.

**Option C:** Subdural hemorrhage would typically present with a more significant mass effect, such as midline shift or a large hemorrhage, which is not present in this case.

**Option D:** Multiple infarcts would not typically present with hemorrhages on CT scan, and the patient's external injuries and lack of midline shift make this diagnosis less likely.

**Clinical Pearl / High-Yield Fact**
In patients with traumatic brain injury, the absence of midline shift on CT scan does not rule out significant brain injury, and other signs such as compressed basal cisterns and microhemorrhages should be carefully evaluated.

**✓ Correct Answer: B. Diffuse axonal injury**