Nuclear reactions are controlled so that there is no explosion (like what happened to Japan World War II) but the principle way to control then heat generated and cool the rods used in thevnuclear reactions is water! The water is circulate around the rods until it turns to steam. The steam is captured and is channeled through pipes to a turbine electrical generator. The turbine spins around very fast generating thousand of kilowatts of electrical energy which runs down copper or aluminum wires to your house. So the answer is B
