The development of a zygote into a baby involves pre-embryonic development for the first 2 weeks, followed by embryonic development for the next 6 weeks, and finally fetal development until the baby is born. When is the developing baby considered a fetus? Answer
a. When most major organ systems have formed; the neural system forms during the fetal stage
b. When all major organ systems have formed
c. Once gastrulation is complete
d. After the neural tube forms
