**Core Concept**
The underlying principle being tested is the clinical presentation and diagnosis of a **pituitary tumor**, specifically a **prolactinoma**, which is a type of **adenoma** that secretes **prolactin**. This condition affects the **hypothalamic-pituitary axis**, leading to various endocrine and neurological symptoms.

**Why the Correct Answer is Right**
A **prolactinoma** is likely the correct diagnosis due to the patient's symptoms of **galactorrhoea** (spontaneous milk production) and **menstrual irregularity**, which are common presentations of hyperprolactinemia. The **bitemporal superior quadrantanopia** and **primary optic atrophy** suggest a **space-occupying lesion** in the **sella turcica**, compressing the **optic chiasm**. This is consistent with a **pituitary macroadenoma**.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, assuming it's an incorrect choice.
**Option B:** Not provided, assuming it's an incorrect choice.
**Option C:** Not provided, assuming it's an incorrect choice.
**Option D:** Not provided, assuming it's an incorrect choice.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **prolactinomas** are the most common type of **pituitary adenoma**, and they often present with **hyperprolactinemia**-related symptoms.

**Correct Answer:** D. Prolactinoma