Once a Baby Is Conceived, How Can Genetic Abnormalities Be

Once a baby is conceived, how can genetic abnormalities be detected?

A) by blood testing of the fetus in the second trimester
B) by amniocentesis, because it is the only way to detect abnormalities prenatally
C) by at least three relatively low-risk procedures that can be used to detect many types of abnormalities
D) by several procedures that can be used to detect many types of abnormalities, although most pose considerable risk to the fetus