Q9

Control rods and moderators play a key role in controlling the rate of fission in nuclear reactors.

Which row of the table correctly shows how this is achieved?

	Control Rod	Moderator
A.	By absorbing neutrons.	By slowing down fast neutrons to thermal speeds.
B.	By absorbing neutrons.	By speeding up slow neutrons so that a chain reaction is sustainable.
C.	By increasing the capture cross-section of neutrons.	By speeding up slow neutrons so that a chain reaction is sustainable.
D.	By increasing the capture cross-section of neutrons.	By slowing down fast neutrons to thermal speeds.