Studying embryology help scientists understand
1) how species reproduce
2) how a species makes food through photosynthesis
3) The early stages of an organisms growth
4) where organisms migrate during their lives

3) The early stages of an organisms growth

Explanation:

Embryology is the study of an organisms prenatal phase. This is the early development stage where the organism is still undergoing some changes before birth in order to become a full grown young one.

It involves the study of different stages that occurs from the point of fertilization to the embryo and foetus formation.

This explanation validates option 3.