Parabolic
Circular
Rectangular
New egged
Answer is Right!
Answer is Wrong!
The correct answer is B. Circular.
A circular sewer is the most efficient cross-section because it has the least amount of surface area for its volume. This means that it has the least amount of frictional resistance to flow, which results in lower pumping costs. Additionally, a circular sewer is the strongest cross-section and can withstand the highest pressures.
A parabolic sewer is the second most efficient cross-section, but it is not as strong as a circular sewer. A rectangular sewer is the least efficient cross-section, and it is also the weakest cross-section. A new egged sewer is not a real cross-section, and it is not a valid option.