If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is

A. Fit for discharge into any open drain B. Foul and contains dissolved and suspended solids C. As good as that from a complete treatment D. None of these

A. 0°C B. 15°C C. 20°C D. 25°C

A. 1 in 5 B. 1 in 10 C. 1 in 15 D. 1 in 20

A. Without entry ladders B. Without manhole covers C. With depths more than 3.5 m D. Having drains at different levels