During Operation of a Nuclear Reactor, the ²³⁸U Nuclei

During operation of a nuclear reactor, the ²³⁸U nuclei

A) slow down the neutrons, thus improving the efficiency of the reactor.
B) are fissioned by the neutrons, thus releasing nuclear energy.
C) absorb neutrons, which causes them to turn into fissionable ²³⁵U.
D) absorb neutrons, which causes them to turn into plutonium.
E) absorb neutrons, which slows down the chain reaction and thus controls the reaction.