**Core Concept**
The question is testing the understanding of the physiology of the menstrual cycle and the role of estrogen and progesterone in inducing withdrawal bleeding. Secondary amenorrhea is characterized by the cessation of menstrual bleeding for 3 months or more in a woman with a history of regular menses. The administration of estrogen and progesterone is a standard diagnostic test to evaluate the integrity of the hypothalamic-pituitary-ovarian axis.

**Why the Correct Answer is Right**
When estrogen and progesterone are administered to a woman with secondary amenorrhea, withdrawal bleeding occurs if the endometrium has been primed by estrogen and progesterone has induced differentiation and growth of the endometrial glands. If withdrawal bleeding does not occur, it suggests a fault in the endometrial response to hormonal stimulation. This is often due to a lack of estrogen receptors or a dysfunctional endometrium, which may be seen in cases of unopposed estrogen exposure or endometrial hyperplasia.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the hypothalamic-pituitary axis is not directly responsible for the endometrial response to estrogen and progesterone. While it is true that the hypothalamus and pituitary gland regulate the menstrual cycle, the endometrial response to hormonal stimulation is a local phenomenon.

**Option B:** This option is incorrect because the ovaries are responsible for producing estrogen and progesterone, but they are not directly involved in the endometrial response to hormonal stimulation.

**Option C:** This option is correct because the endometrium is responsible for responding to estrogen and progesterone. A fault in the endometrial response to hormonal stimulation suggests a problem at the level of the endometrium itself.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that secondary amenorrhea is a symptom, not a diagnosis. A thorough evaluation of the patient's history, physical examination, and laboratory results is necessary to determine the underlying cause of amenorrhea.

**Correct Answer: C.**