The correct answer is B. 2.0.
The ratio of maximum daily sewage flow to the average daily sewage flow is called the peak factor. It is a measure of how much the sewage flow varies throughout the day. The peak factor is typically higher for smaller sewers, as they are more likely to be overloaded during peak flow periods.
For sewer mains of 0.5 to 1 m diameter, the peak factor is typically assumed to be 2.0. This means that the maximum daily sewage flow is twice the average daily sewage flow.
The peak factor is an important factor in the design of sewers. It is used to determine the size of the sewer and the capacity of the pumping stations.
The other options are incorrect. Option A is too low, and options C and D are too high.