To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is_________________?

A. the meta-center should lie above the center of gravity
B. the center of buoyancy and the center of gravity must lie on the same vertical line
C. a righting couple should be formed
D. all the above are correct
E. none of the above is correct

A. 1000
B. 2100
C. 2700
D. 10,000
E. 21,000.

A. comparing two identical equipments
B. designing models so that the result can be converted to prototypes
C. comparing similarity between design and actual equipment
D. hydraulic designs
E. performing acceptance tests