**Core Concept**
Raised intracranial tension (ICT) can lead to various ophthalmic manifestations due to increased pressure within the cranial vault. This increased pressure can cause mechanical effects on the optic nerve, leading to structural changes and clinical symptoms.

**Why the Correct Answer is Right**
The most common ophthalmic manifestation of raised ICT is **papilledema**. Papilledema is characterized by swelling of the optic disc due to increased pressure within the optic nerve sheath. This swelling is caused by the compression of axons within the optic nerve, leading to impaired axoplasmic flow and subsequent optic disc edema. The optic nerve head is particularly susceptible to increased pressure due to its anatomical location within the cranial vault.

**Why Each Wrong Option is Incorrect**
**Option A:** Papillitis is an inflammatory condition affecting the optic disc, which is distinct from the mechanical effects of raised ICT on the optic nerve.
**Option B:** Optic neuritis is an inflammatory condition affecting the optic nerve, which can cause pain and visual loss but is not a direct result of raised ICT.
**Option C:** Retinal detachment is a condition where the retina separates from the underlying retinal pigment epithelium, which can be caused by various factors but is not a direct result of raised ICT.

**Clinical Pearl / High-Yield Fact**
Papilledema is often described as "blown optic disc" due to its characteristic appearance, where the optic disc appears swollen and elevated above the surrounding retinal surface.

**Correct Answer:** C. Papilledema.