= Solution
\b[Delayed <neutrons> are emitted after precursor radioactive transformations, rather than promptly at fission.] Some <neutron>-rich <fission products> undergo beta decay into excited daughter states that can emit a <neutron>. The waiting time is governed chiefly by the precursor's radioactive lifetime, not by a <neutron> moving unusually slowly after it has already been emitted.
Although their fraction is small, <delayed neutrons> introduce a much slower population timescale into the <nuclear chain reaction>. In the delayed-<neutron>-controlled regime, changes can therefore develop over times comparable with precursor lifetimes rather than only the <prompt neutron generation time>. That timescale separation is central to qualitative reactor controllability. It does not imply that every positive-reactivity transient is slow.
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