Answer: The correct answer for the fill in the blank is- A) Nuclear power.
Renewable sources of energy are those resources that can be replenished or renewed naturally. They do not run off that is they are inexhaustible.
Example of renewable sources- Solar energy, wind energy, geothermal energy, hydro-power.
On the other hand, non renewable source of energy are exhaustible and can not be replenished naturally.
Nuclear power ( resulted due to heat produced in the fission of atoms) is non- renewable source of energy. This is because the fuel that is used in most of the nuclear fission reactions is uranium, which is found in fixed amount on earth.