In a nuclear reaction, the fuel pellets are split using what ? This also causes a chain reaction

A nuclear reactor is driven by the splitting of atoms, a process called fission, where a particle (a 'neutron') is fired at an atom, which then fissions into two smaller atoms and some additional neutrons. ... Two examples of nuclear fissioning of uranium-235, the most commonly used fuel in nuclear reactors.

Explanation:

i think the answer is b.

b. lithosphere, asthenosphere, mesosphere   is the answer most likely