Why do many historians believe history is cyclical? a Certain religions create the circumstances that force people to keep making the same mistakes.
b Human nature remains constant in many ways.
c Very few people study history.
d Powerful leaders prefer that events are cyclical.

Hi! after fertilization occurs, the zygote goes through mitosis and then differentiation (aka specialization of cells) to have a variety of cells that perform different functions. this allows for the creation of tissues and so on, all of which were once stem cells with no specific function.i hope i !