Answer:
B
Explanation:
In a chain reaction of radioactive decay, more and more neutrons are produced that bombard more nuclei causing them to split (decay). This how a nuclear core releases more and more energy. The purity of the radioactive core determines the chain reaction and rate of energy released. A few impurities (nonfissionable material) are introduced to absorb excess neutrons (and regulate their numbers) to prevent overheating of the core.
