Test-tube babies are produced in a process when:

• A. Fertilizing egg is removed from the body of the female and fertilized with the husband's sperm outside in vitro culture and then the zygote is transferred back to mother's uterus.
• B. External fertilization and development in vitro culture till 32 cell stage before putting the embryo back into mother's uterus.
• C. Complete development of a baby take place in vitro.
• D. Development upto 32 cell stage of embryo takes place and its transplantation in the uterus of a surrogate mother occurs.