What Is Surrogacy as a Treatment for Infertility

What is surrogacy as a treatment for infertility?

A) Donor sperm is substituted for the father's sperm, which is defective in some way.
B) Donor eggs are substituted for the mother's eggs, which are defective in some way.
C) An embryo which is unwanted is carried to term anyway, and the baby adopted by a couple who are not his or her biological parents.
D) A woman other than the biological mother is impregnated by either artificial insemination or in vitro fertilization and carries the baby to term for its biological parents.
E) Adoption of an unwanted or orphaned child