Answer:
zygote.
Explanation:
when an egg gets fertilized in the fallopian tube, it becomes a zygote. the zygote then travels down the fallopian tube to the uterus. about 4-7 days.
Morula: On day four, the zygote becomes a morula
Blastocyst: On day five, the morula becomes a blastocyst
Implantation: The blastocyst burrows into the uterine lining, which is called implantation
Embryo: Once implanted, the group of cells that will become a baby is called an embryo