**Core Concept**
The question tests the understanding of risk factors for **endometrial cancer**, a type of cancer that begins in the uterus. **Hormonal imbalance**, particularly **estrogen** dominance, plays a significant role in its development.

**Why the Correct Answer is Right**
**Obesity** is a correct risk factor because it leads to increased **estrogen** levels due to **aromatase** activity in adipose tissue, which converts **androgens** to **estrogens**. This increase in **estrogen** can stimulate the growth of the **endometrium**, potentially leading to cancer.

**Why Each Wrong Option is Incorrect**
**Option B:** Pregnancy before 20 years of age is actually protective against endometrial cancer, as it reduces the overall number of **menstrual cycles** and thus the cumulative exposure to **estrogen**.
**Option C:** While **PCOD (Polycystic Ovary Syndrome)** is associated with **hyperestrogenism** and could theoretically increase the risk of endometrial cancer, its direct link as a risk factor is less clear compared to obesity.
**Option D:** Combined **OC pills (Oral Contraceptives)** are generally protective against endometrial cancer because they regulate menstrual cycles and reduce **estrogen** exposure.
**Option E:** Artificial menopause, or **premature ovarian failure**, would decrease the risk of endometrial cancer due to reduced **estrogen** levels.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **unopposed estrogen** exposure is a significant risk factor for endometrial cancer, and conditions or factors that increase **estrogen** levels without the balancing effects of **progesterone** can elevate this risk.

**Correct Answer:** A. Obesity