The stage transferred into the uterus after induced fertilization

The stage transferred into the uterus after induced fertilization of ova in the laboratory is

1. Zygote
2. Embryo at 4 blastomere stage
3. Embryo at 2 blastomere stage
4. Morula

In Intra-Uterine Transfer (IUT) embryo with more than 8-blastomeres stage (morula) is used for transfer into the uterus.