What is considered to be the first evidence of differentiation in the cells of an embryo?

A. cell division occurring after fertilization

B. the occurrence of mRNAs for the production of tissue-specific proteins

C. determination of specific cells for certain functions

D. changes in the size and shape of the cell

E. changes resulting from induction

Option (B).

Explanation:

The process of cell differentiation in the embryonic stage is important for the cell to differentiate into a specific cell type. The cell differentiation also occurs in the adult stages also.

Various experiments have been done to find the evidence of cell differentiation. The occurrence of the specific mRNAs for the formation of tissue specific proteins provide the evidence that cell differentiation occurs in the embryonic stage.

Thus, the correct answer is option (B).