Test tube babies are produced by

• A. Fertilising the egg removed from the body of the female with the husband's sperm outside in vitro culture. The zygote is transferred back
• B. External fertilisation and development in vitro culture till 32 cells stage before putting the embryo back into mother's uterus
• C. Complete development of a baby in vitro
• D. Development upto 32 cells stage and transplanting embryo in the uterus of a surrogate mother