Choose the correct answer:
1. On basis of the following features, identify the correct option.
i. It is used as a moderators in nuclear reactor.
ii. It is used to slow down the fast moving neutrons to control the chain reaction in the reactor.
i. It is used as a moderators in nuclear reactor.
ii. It is used to slow down the fast moving neutrons to control the chain reaction in the reactor.
2. Boron rods in a nuclear reactor are used to __________.