Which has been observed in the study of embryology? species whose embryos have similar traits rarely have a common ancestor. species whose embryos have similar traits always have similar body forms as adults. all traits present in early embryos remain throughout development. some traits in certain embryos disappear as the embryo develops.

All traits present in early embryos remain throughout development.

Explanation:

Embryology came from two Greek word embryon, "the unborn, embryo"; and-logia. It is the branch of biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses.

Some features of Embryology:

Embryology is the study of embryos.Embryos of different animals such as mammals, birds, fish, reptiles, etc. look alike; that is, they are very similar. Many traits of one type of animal appear in the embryo of a different kind of animal.The similarity in embryos among animals shows commonality in terms of evolutionary relationship, implying the presence of common ancestry.Some traits in individual embryos disappear as the embryo develops; for example, the gill slits in human embryos go as the embryo develops.

Rna polymeras should attache to the promoter.