## **Core Concept**
Chorionic villi sampling (CVS) or chorionic villi biopsy is a prenatal test in which a sample of chorionic villi is removed from the placenta for testing. This test can detect chromosomal abnormalities and other genetic disorders. It is typically performed between 10 to 12 weeks of gestation.

## **Why the Correct Answer is Right**
The correct answer, although not directly provided, relates to understanding what CVS can and cannot do. CVS is primarily used for genetic testing and can diagnose conditions such as Down syndrome, trisomy 18, and certain genetic mutations. It does not directly assess fetal anatomy or detect structural anomalies like certain congenital heart defects or neural tube defects, which are better evaluated with ultrasound.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Without specific details on option A, we can't directly address its accuracy. However, if it pertains to the diagnostic capabilities of CVS, one must consider what CVS is known for, such as genetic diagnosis.
- **Option B:** Similarly, without specifics, if option B suggests CVS can diagnose structural anomalies, it would be incorrect as CVS is not used for this purpose.
- **Option C:** If option C mentions genetic diagnosis, it could be a correct statement about CVS, making other options that contradict this incorrect.
- **Option D:** If option D suggests CVS is performed late in pregnancy, it would be incorrect as CVS is typically done between 10-12 weeks.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that CVS is primarily used for genetic testing and does not provide detailed anatomical assessment of the fetus. This test can help in early detection of genetic abnormalities, allowing for informed decision-making.

## **Correct Answer: C.**