**Core Concept**
The most common genetic cause of spontaneous abortion is related to **chromosomal abnormalities**. These abnormalities can lead to non-viable pregnancies, often resulting in miscarriage. **Cytogenetic** studies are crucial in identifying these anomalies.

**Why the Correct Answer is Right**
Although the specific correct answer option is not provided, the most common genetic cause of spontaneous abortion is generally related to **chromosomal anomalies**, such as **aneuploidy** (e.g., trisomy) or **translocations**. These genetic errors can disrupt normal fetal development, leading to miscarriage.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option details, it's challenging to provide a precise explanation, but typically, options that do not involve chromosomal abnormalities would be incorrect.
**Option B:** Similarly, without specifics, any option not directly related to genetic or chromosomal issues would not be the primary cause of spontaneous abortion.
**Option D:** This option would also be incorrect if it does not involve a recognized genetic cause of miscarriage.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **chromosomal abnormalities** account for approximately half of all first-trimester miscarriages, with **aneuploidy** being a major contributor. Recognizing the role of genetics in spontaneous abortion is crucial for counseling and management.

**Correct Answer:** D. Chromosomal abnormalities.