## Core Concept
The core concept being tested here involves the indications for **Mifepristone (RU 486)**, a medication primarily used for its **anti-progestin** effects. Mifepristone works by blocking the action of **progesterone**, a hormone necessary to maintain pregnancy. This mechanism underlies its use in medical termination of pregnancy and other related conditions.

## Why the Correct Answer is Right
Mifepristone (RU 486) is well-known for its role in **medical abortion** within the first 10 weeks of pregnancy. It is also used for **Cushing's syndrome**, particularly in cases where surgery is not an option or has failed. The drug's anti-progestin effects make it useful in managing conditions like **endometriosis** and **uterine fibroids** by reducing the growth of endometrial and fibroid tissues. However, its use in **ectopic pregnancy** is not standard due to the lack of efficacy in resolving the ectopic pregnancy and potential for severe bleeding.

## Why Each Wrong Option is Incorrect
- **Option A:** Mifepristone is indeed used for **early medical abortion**, making this option an indication for RU 486.
- **Option B:** It is used in the management of **Cushing's syndrome**, particularly for patients with endogenous Cushing's syndrome who have had or are not candidates for other treatments.
- **Option C:** Mifepristone has applications in treating **severe psoriasis**, although this is less commonly discussed than its use in pregnancy termination or Cushing's syndrome.
- **Option D:** **Ectopic pregnancy** is not a standard indication for mifepristone. Ectopic pregnancies are typically managed with **methotrexate** or surgical intervention.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while mifepristone is effective for medical abortion and certain other conditions, its use in **ectopic pregnancy** is not recommended due to the risk of severe hemorrhage and the ineffectiveness in resolving the ectopic pregnancy.

## Correct Answer: D. Ectopic pregnancy.