How Can Prenatal Testing and Genetic Counseling Avoid the Whole

How can prenatal testing and genetic counseling avoid the whole issue of germ-line gene therapy, while still identifying "bad" genes?

A) Defective eggs and sperm can be identified and excised from the parents prior to conception.
B) Only eggs and sperm free of the bad gene can be combined in the lab and only the resulting healthy embryos implanted.
C) The "bad" genes can be identified, along with the risk of passing them on, and then the parents can decide whether to have children at all, or only allow embryos screened to be "healthy" to come to term.
D) If all embryos can be screened for "bad" genes, all those with the "bad" genes can be prevented from developing.
E) If all parents are screened for defective genes, those who have those genes can be prevented from having children.