If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is

If the diameter of sewer is 225 mm, the gradient required for generati

1.	If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is
A.	1 in 60
B.	1 in 100
C.	1 in 120
D.	none of these.
Answer» D. none of these.