**Core Concept**
Amniocentesis is a prenatal diagnostic procedure that involves the withdrawal of a sample of amniotic fluid from the uterus to detect fetal abnormalities. The procedure is typically performed between 15 and 20 weeks of gestation.

**Why the Correct Answer is Right**
Amniocentesis is mostly performed between 16 and 18 weeks of gestation, as this allows for the detection of chromosomal abnormalities such as Down syndrome and other genetic disorders. The procedure involves the insertion of a needle into the amniotic sac to collect a sample of amniotic fluid, which is then analyzed for fetal DNA and other markers. The accuracy of the test increases with the gestational age, and 16-18 weeks is considered the optimal time for amniocentesis.

**Why Each Wrong Option is Incorrect**
* **Option A:** 8 weeks - This is too early for amniocentesis, as the risks associated with the procedure are higher and the accuracy of the test is lower.
* **Option B:** 24 weeks - While amniocentesis can be performed at this gestational age, it is not the optimal time, as the risks associated with the procedure increase and the accuracy of the test may decrease.
* **Option C:** 12 weeks - This is too early for amniocentesis, as the risks associated with the procedure are higher and the accuracy of the test is lower.

**Clinical Pearl / High-Yield Fact**
It is essential to note that amniocentesis should only be performed after 15 weeks of gestation, as this reduces the risk of miscarriage and other complications associated with the procedure.

**Correct Answer:** C. 16 weeks