In the case of test tube babies, the correct option is option 4 - the egg is fertilized outside the mother`s body. This process is known as in vitro fertilization (IVF). In IVF, the egg is fertilized by sperm in a laboratory dish, and the resulting embryo is then transferred to the mother`s uterus for implantation and further development. The term "test tube babies" is often used to describe this process, although it is a bit of a misnomer, as the actual fertilization and development occur in a Petri dish rather than a test tube. Option 1 is incorrect because the fertilization does not take place in the uterus. Option 2 is also incorrect because the embryo is not fully developed in a test tube or laboratory dish. Option 3 is also incorrect because the embryo is usually transferred to the uterus sooner than 2 months after fertilization.