Question

consider the following statements;
The role of the gravel bed in a rapid sand filter is
1. To filter out large suspended particles
2. To support the sand bed above it
3. To prevent the escape of sand particles
4. To uniformly distribute the backwash water
5. To prevent the algal growth
Which of these statements are correct?
1) 1,2,3,4 and 5
2) 2,3 and 4 only
3) 3,4 and 5 only
4 1,2 and 3 only​

Answer 1

Explanation:

answer is 2) 2,3 and 4 only