A couple wants a second child that is biologically related to them. They have been trying for five years. The wife is 45 years old and healthy, with no history of sexually transmitted diseases. Three rounds of artificial insemination with her husband's sperm have failed. There is no evidence of any problem with her husband's sperm count or motility. What would be the most likely next step? a. Another round of artificial insemination with the husband's sperm
b. Artificial insemination is donor sperm
c. In vitro fertilization using the wife's egg in donor sperm
d. In vitro fertilization using a donor egg and her husband's sperm