This UV method for cleaning is used in various water purification system. Can anyone tell this answer

What is the role of ultraviolet (UV) radiation in the water purification systems?
1. It inactivates/kills the harmful microorganism in water.
2. It removes all the undesirable odours from the water.
3. It quickness the sedimentation of solid particles, removes turbidity and improves the clarity of water.

Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3