**Core Concept**
The question is testing the student's knowledge of anti-progesterone drugs, which are a class of medications used to counteract the effects of progesterone, a hormone involved in the female menstrual cycle and embryogenesis.

**Why the Correct Answer is Right**
Mifepristone, also known as RU486, is a potent anti-progesterone drug that works by competitively binding to the progesterone receptor in the myometrium, endometrium, and embryonic tissue. This binding action blocks the action of endogenous progesterone, leading to the termination of pregnancy. Mifepristone is used in combination with a prostaglandin analog for medical abortion.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct anti-progesterone drug.
**Option B:** This option is incorrect because it is not a recognized anti-progesterone drug.
**Option C:** This option is incorrect because it is not a correct anti-progesterone drug.

**Clinical Pearl / High-Yield Fact**
Mifepristone is also used in the treatment of Cushing's syndrome, a hormonal disorder caused by excess cortisol production. Its use in this condition is based on its ability to block cortisol receptors, leading to a decrease in cortisol levels.

**Correct Answer:** C. Mifepristone.