Adult skin cells can no longer become other types of cells because they have already undergone (1 point) prophase ,chloroplast, chromatid, differentiation cytokinesis it is not differentiation that is not the right answer

This would be in fact differentiation. differentiation is the process changing less specialized cells to more specialized. in differentiation cells develop to possess a more distinct form and function.completely differentiated cells cannot further differentiate to any other type of the cells. adult skin cells have their own function and structure so they are  completely differentiated.