The biochemical oxygen demand (BOD) level is a measure of the amount of dissolve

The biochemical oxygen demand (BOD) level is a measure of the amount of dissolved oxygen consumed by microorganisms while decomposing organic matter in water over a specific period, usually 5 days at 20°C. Higher BOD levels indicate higher concentrations of organic pollutants in the water, which can lead to greater oxygen depletion and more significant environmental impact. Therefore, the sample with the highest BOD level is the most polluted.
In this case, the BOD levels of the three samples are as follows:
Sample A: 60 mg/L
Sample B: 20 mg/L
Sample C: 500 mg/L
Comparing these values, it’s evident that Sample C has the highest BOD level of 500 mg/L. Therefore, Sample C is the most polluted among the three samples.