**Core Concept**
Papilloedema is the swelling of the optic disc due to increased intracranial pressure (ICP). The condition can be caused by various factors, including space-occupying lesions, hydrocephalus, or other conditions that lead to elevated ICP. In this scenario, the CT scan shows normal ventricles, which rules out hydrocephalus as a cause.

**Why the Correct Answer is Right**
The correct answer is likely **Idiopathic Intracranial Hypertension (IIH)**, also known as pseudotumor cerebri. IIH is a condition characterized by elevated ICP without any identifiable cause, such as a tumor or hydrocephalus. The pathophysiology of IIH involves impaired cerebrospinal fluid (CSF) absorption, leading to increased ICP and subsequent papilloedema. The normal ventricles on CT scan support this diagnosis, as IIH typically does not involve ventricular enlargement.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because hydrocephalus is typically associated with enlarged ventricles on imaging, which is not the case in this scenario.
* **Option B:** This option is incorrect because normal pressure hydrocephalus (NPH) is a condition characterized by enlarged ventricles and gait disturbance, which is not consistent with the normal ventricles and bilateral papilloedema in this patient.
* **Option C:** This option is incorrect because a space-occupying lesion would typically be visible on CT scan, and the question states that the ventricles are normal.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that idiopathic intracranial hypertension (IIH) is a diagnosis of exclusion, and other causes of elevated ICP should be ruled out before making this diagnosis.

**Correct Answer:** D.