**Core Concept**
The question tests the student's knowledge of **iatrogenic causes of adrenal insufficiency**, specifically Addison's disease. Addison's disease is a rare disorder of the adrenal glands where they do not produce enough **cortisol** and, in some cases, **aldosterone**.

**Why the Correct Answer is Right**
The correct answer is related to a drug that can cause adrenal insufficiency by inhibiting the production of cortisol. This is often seen with **ketoconazole**, an antifungal medication that can inhibit **cytochrome P450 enzymes**, leading to decreased production of cortisol.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect as it is not typically associated with Addison's disease.
**Option B:** Incorrect as it is not commonly linked to adrenal insufficiency.
**Option C:** Incorrect because, although it affects steroid synthesis, it is not the most direct cause.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that any drug affecting the **hypothalamic-pituitary-adrenal axis** can potentially lead to adrenal insufficiency.

**Correct Answer:** D. Ketoconazole.