The substance that slows down the neutrons to have controlled chain reaction during nuclear energy production is called:

Correct option is C

In nuclear reactors, a moderator is a material that slows down fast neutrons, making them more likely to sustain a chain reaction by causing further fission. Common moderators include heavy water (D2O), ordinary water (H2O), and graphite. Moderators are essential in nuclear reactors to maintain a controlled and sustained fission reaction.
Information Booster:
1. Moderator: A material that slows down neutrons, enabling sustained fission in nuclear reactors.
2. Control rods: Devices in nuclear reactors that absorb neutrons and help regulate the reaction rate.
3. Nuclear fission: A reaction in which the nucleus of an atom splits into smaller parts, releasing energy.
4. Chain reaction: A self-sustaining reaction where neutrons released from fission cause additional fissions.
Additional Knowledge:
· (a) Controller: Incorrect, the controller is part of the system to manage the fission rate.
· (b) Inhibitor: Incorrect, inhibitors prevent reactions but don’t slow neutrons.
· (c) Moderator: Correct, moderators slow down neutrons to facilitate a controlled chain reaction.
· (d) Reducer: Incorrect, not a term used in nuclear physics.