Which fact is true during a fission chain reaction?(1 point)

The correct response is:

The number of freely-moving neutrons increases over time.

During a fission chain reaction, when heavy atomic nuclei (like uranium-235 or plutonium-239) undergo fission upon absorbing a neutron, they split into smaller nuclei and release energy, additional neutrons, and other particles. The neutrons released can then go on to induce fission in other nearby nuclei, continuing the chain reaction. Thus, the number of freely-moving neutrons increases as the reaction proceeds, at least initially, until the reaction is controlled or reaches a stable state.