Which statement best describes control rods?

They are unmovable pieces.

They are inert.

They supply neutrons to start the nuclear chain reaction.

They drive the generator

Control rods are rods, plates, or tubes containing a neutron absorbing material (material with high absorbtion cross-section for thermal neutron) such as boron, hafnium, cadmium, etc., used to control the power of a nuclear reactor. so the statement that describe a control rod is:Control rods are lowered into the reactor to slow down the reaction by absorbing neutrons.

B. They are invert. I just took that question.