What is the role of Ultra-violet (UV) radiation in the water purification systems?

1. It inactivates, kills the harmful microorganisms in water.

2. It removes all the undesirable odours from the water.

3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water

Which of the statements given above is/are correct?

I.A.S. (Pre) 2012