In test tube baby or in vitro fertilisation technique, the ovum is fertilised with the sperm outside the body of a woman providing the ovum with the same environmental conditions as it would have got inside the uterus. The zygote formed is grown inside a culture and when embryo (having 8 or more blastomeres) is formed, it is then implanted into uterus where it develops into foetus. So, the correct answer is 'Fertilisation of the egg is completed outside the body, the fertilised egg is then placed in the womb of the mother where the gestation is completed'.