Answer:
I hope you spend that much time, happily at peace.
Cell differentiation<span> is how generic embryonic </span>cells <span>become specialized </span>cells. This occurs through a process<span> called gene expression. Gene expression is the specific combination of genes that are turned on or off or also known as expressed or repressed, and this is what dictates how a </span>cell<span> works. </span>
D, because the atomic mass number for carbon is 6