**Core Concept**
Increased intracranial tension (ICT) is a condition characterized by elevated pressure within the cranial vault, which can lead to various neurological symptoms and complications. The underlying pathophysiology involves impaired cerebrospinal fluid (CSF) circulation, altered venous drainage, and increased cerebral blood volume.

**Why the Correct Answer is Right**
The correct answer is related to the clinical features of raised ICT. One of the key distinguishing features of raised ICT is the presence of papilledema, which is the swelling of the optic disc due to increased intracranial pressure. This is often accompanied by other symptoms such as headache, nausea, vomiting, and visual disturbances. The increased pressure can also disrupt the normal flow of CSF, leading to hydrocephalus or transtentorial herniation.

**Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because it is a feature of raised ICT. Cushing's triad is a classic sign of increased intracranial pressure, consisting of bradycardia, hypertension, and irregular breathing.
* **Option B:** is incorrect because it is a feature of raised ICT. Altered mental status is a common symptom of increased intracranial pressure, ranging from mild confusion to coma.
* **Option D:** is incorrect because it is a feature of raised ICT. Headache is a common symptom of increased intracranial pressure, often described as a dull, aching sensation.

**Clinical Pearl / High-Yield Fact**
One of the key differences between raised ICT and other causes of headache is the presence of papilledema. Remember the mnemonic "P-A-C-H-E" to associate papilledema with raised ICT: Papilledema, Altered mental status, Cushing's triad, Headache, and Elevation of CSF pressure.

**Correct Answer: D. Headache**