**Core Concept**
The question is testing the risk of progression from complex atypical endometrial hyperplasia (CAH) to endometrial cancer in postmenopausal women. This concept is relevant to the diagnosis and management of endometrial hyperplasia, a common gynecological condition.

**Why the Correct Answer is Right**
Complex atypical endometrial hyperplasia (CAH) is a precancerous condition characterized by the proliferation of endometrial glands with nuclear atypia. The risk of progression to endometrial cancer is significantly higher in postmenopausal women due to the lack of hormonal regulation and the presence of unopposed estrogen. The risk of progression from CAH to endometrial cancer in postmenopausal women is estimated to be around 29%. This is because the postmenopausal endometrium is exposed to high levels of estrogen, which can stimulate the growth of malignant cells.

**Why Each Wrong Option is Incorrect**
**Option A:** 3% is too low, as it does not accurately reflect the increased risk of progression in postmenopausal women.
**Option B:** 8% is still underestimating the risk, as it does not account for the higher risk of progression in postmenopausal women.
**Option C:** 15% is closer to the actual risk, but still underestimates the risk of progression in postmenopausal women.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the risk of progression from CAH to endometrial cancer is significantly higher in postmenopausal women, and therefore, they should be managed more aggressively with hysterectomy or other definitive treatments.

**✓ Correct Answer: D. 29%**