**Core Concept**
Diethylstilbestrol (DES) is a synthetic estrogen used in the past for various indications, including pregnancy complications and hormone replacement therapy. However, its use in pregnancy has been associated with several congenital anomalies in the offspring.

**Why the Correct Answer is Right**
DES exposure in utero has been linked to a range of reproductive and developmental abnormalities, primarily due to its estrogenic effects on the fetus. The most notable defects associated with DES exposure include clear cell adenocarcinoma of the vagina and cervix, reproductive tract abnormalities such as vaginal and cervical anomalies, and infertility issues in both males and females. The exact mechanisms underlying these defects are not fully understood but are thought to involve the disruption of normal reproductive development and the induction of abnormal cell growth.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because DES exposure has been well-documented to cause clear cell adenocarcinoma, a rare and aggressive type of cancer.
* **Option B:** This option is incorrect because DES exposure has been associated with a range of reproductive tract abnormalities, including vaginal and cervical anomalies.
* **Option C:** This option is incorrect because DES exposure has been linked to infertility issues in both males and females, although the exact mechanisms are not fully understood.

**Clinical Pearl / High-Yield Fact**
It's essential to note that DES exposure has been largely discontinued due to its associated risks, and current medical guidelines recommend against its use in pregnancy. However, individuals exposed to DES in utero may still be at risk for various reproductive and developmental abnormalities.

**Correct Answer:** A.