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

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

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.