ANS:A - 1.5

In wastewater engineering, the ratio of maximum sewage flow to average sewage flow for trunk mains, especially those with diameters larger than 1.25 meters, is typically higher than 1.5. A ratio of 1.5 would mean that the maximum sewage flow is only 1.5 times the average sewage flow. However, in reality, trunk mains are designed to accommodate peak flows that are significantly higher than average flows to ensure that the system can handle surges in wastewater volume during periods of heavy rainfall, rapid urbanization, or other peak demand situations. A ratio of 2.0 to 3.0 is more common and provides a buffer to accommodate variations in flow rates while maintaining system reliability and performance. Therefore, the explanation for an answer of 1.5 doesn't align with typical engineering practices in wastewater management.