To prevent the possibility of erosion and piping, following approaches are used:1. By providing cut off wall at downstream side2. Increasing the flow path by providing impervious blanket3. Use of protective filterWhich of these statements are correct?

To prevent the possibility of erosion and piping, following approaches

1.	To prevent the possibility of erosion and piping, following approaches are used:1. By providing cut off wall at downstream side2. Increasing the flow path by providing impervious blanket3. Use of protective filterWhich of these statements are correct?
A.	1, 2 and 3
B.	1 and 2
C.	2 and 3
D.	1 and 3
Answer» B. 1 and 2