Answer:
A- zygote, embryo , fetus
Explanation:
The "zygote" is formed after the egg cell and the sperm cell unite. This is called the "fertilization stage." After which, the zygote continuously divides and becomes a "blastocyte." This happens as it moves down towards the uterus. It only becomes an "embryo" after it is able to implant in the uterine wall. It further continues to develop until it is called a "fetus" during the 8th week.
The fetal development then starts with the zygote, followed by the embryo and then the fetus.
