Answer:
The correct answer will be option-D
Step-by-step explanation:
Stem cells are the cells which have the ability to form different types of cells. They differentiate and specializes to perform different functions in the body and thus forms the different cells.
The differentiation and specialization are controlled at the gene level by different patterns of gene expression. The pattern of gene expression is not fully understood during development but research have shown that the gene expression is influenced by the different environmental signals and internal regulators.
Thus, option-D is the correct answer.