उत्तर : 2. "Neutron"
व्याख्या :

Answer: B) Neutron Explanation: In nuclear physics, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei). The fission process often produces free neutrons and releases a very large amount of energy.   Thus, The Nuclear Fission is caused by the impact of Neutrons.