Control rods made of cadmium are suddenly inserted deeper into the core of a nuclear reactor that had been operating at steady power. What immediate qualitative effect will this have on the effective multiplication factor k and the power output?
a) k remains exactly 1 and the power output stays unchanged
b) k becomes less than 1 and the power output falls
c) k becomes greater than 1 and the power output rises
d) k becomes zero and the reaction stops instantaneously