Which of the following instrument can be used for measuring speed of a submarine moving in deep sea_________________?

A. Imhoff tanks
B. Trickling filters
C. Sludge sedimentation tanks
D. None of these

A. 20% of the design discharge
B. Slightly less than 5% of the design discharge
C. Slightly more than 5% of the design discharge
D. None of these

A. Perpendicular to the direction of flow
B. Parallel to the direction of flow
C. At an angle 30° to 60° to the direction of flow
D. None of these