**Core Concept**
Endometrial hyperplasia is a condition characterized by the abnormal proliferation of the endometrial glands, often leading to an overgrowth of the endometrium. This condition is typically associated with hormonal influences, particularly an excess of estrogen relative to progesterone.

**Why the Correct Answer is Right**
The correct answer is related to the estrogen-progesterone balance in the body. Estrogen promotes the growth of the endometrium, while progesterone helps to maintain a balance by inhibiting further growth. When estrogen levels are high and progesterone levels are low, the endometrium becomes hyperplastic. This imbalance can be caused by a variety of factors, including unopposed estrogen replacement therapy, polycystic ovary syndrome (PCOS), and certain genetic disorders.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the hormonal influences that cause endometrial hyperplasia.
**Option B:** This option is incorrect because it refers to a different condition that affects the endometrium, but is not directly related to hormonal imbalances.
**Option C:** This option is incorrect because it refers to a condition that affects the ovaries, but is not directly related to endometrial hyperplasia.

**Clinical Pearl / High-Yield Fact**
It's essential to note that unopposed estrogen replacement therapy can increase the risk of endometrial hyperplasia and cancer. Therefore, progesterone is often added to estrogen replacement therapy to maintain a balance and prevent these complications.

**Correct Answer: D.** Unopposed estrogen replacement therapy is a common cause of endometrial hyperplasia.