Both Members of an Expecting Couple Are Carriers of Tay-Sachs

Both members of an expecting couple are carriers of Tay-Sachs disease, which is an autosomal recessive condition that causes deterioration of nervous function within several months after birth and usually death by age 4. The couple wants to avoid having a child with Tay-Sachs disease, and a DNA test is available to detect the mutant allele. It is early in the pregnancy, and the couple is willing to abort the fetus if it is homozygous for the allele that causes Tay-Sachs disease. However, the couple wishes to have the abortion performed as early as possible if one is to be done. Which would be the MOST appropriate test to determine the genotype of the fetus?

A) amniocentesis
B) newborn screening
C) preimplantation genetic diagnosis
D) heterozygote screening
E) chorionic villus sampling