Cells need to reproduce for growth, repair, or replacements. Cells divide whenever a tissue / organ / organism is growing or needs repair.
Hope this helps :)
For much of the last quarter century, the leading theory of the driving force behind tectonic plate motions envisaged large scale convection currents in the upper mantle, which can be transmitted through the asthenosphere. So letter C. is the Answer.
I think its b or c im 80.99% sure