Answer:
The most appropriate answer would be D. position of genes in chromosomes.
Cell differentiation and development refers to the phenomenon by which a cell becomes specialized to perform specific functions.
It is achieved by highly regulated gene expression of the cell.
Each cell in a multi-cellular organism contains same genetic material (same number of chromosomes as well as genes) however, different sets of genes are expressed in different types of cells.
For example, heart cells express different sets of genes than the nerve cells.
Thus, the position of genes in chromosomes play important role in cell differentiation.
