Final Answer:
The least invasive form of parental genetic testing is Maternal Blood Testing. Option 2 is correct answer.
Step-by-step explanation:
Maternal Blood Testing, also known as non-invasive prenatal testing (NIPT), is a method of genetic testing that analyzes cell-free DNA in the mother's blood to assess the risk of certain genetic conditions in the fetus. This testing can provide information about chromosomal abnormalities, such as Down syndrome, without the need for invasive procedures that carry a higher risk of complications. In contrast, procedures like Chorionic Villus Sampling (CVS) and Amniocentesis involve the collection of samples from the placenta or amniotic fluid, respectively, and carry a slightly higher risk of miscarriage. Heterozygote Screening and Preimplantation Genetic Diagnosis are not typically considered parental genetic testing methods; the former is more related to carrier status, while the latter is performed on embryos during in vitro fertilization.
Option 2 is the answer.