To fulfill the adequate permeability the D15 of filter/D15 of foundation ratio should be greater than __________

To fulfill the adequate permeability the D15 of filter/D15 of foundat

1.	To fulfill the adequate permeability the D15 of filter/D15 of foundation ratio should be greater than __________
A.	5
B.	10
C.	15
D.	20
Answer» B. 10