Answer:
Zygote
Explanation:
A zygote, also known as a fertilized ovum or fertilized egg, is the union of a sperm cell and an egg cell. The zygote begins as a single cell but divides rapidly in the days following fertilization. The zygote’s single cell contains all of the 46 necessary chromosomes, getting 23 from the sperm and 23 from the egg.The zygote phase is brief, lasting only about four days. Around the fifth day, the mass of cells becomes known as a blastocyst.