Question

four water samples were subjected to bod analysis. which sample had the lowest level of organic material? mg/l dissolved oxygen time (days)

Explanation:

Step1: Understand BOD concept

Biochemical Oxygen Demand (BOD) is related to the amount of organic matter. Lower BOD means lower organic - matter content. The steeper the slope of the line representing the decrease in dissolved oxygen over time in a BOD test, the higher the BOD (more organic matter being decomposed and consuming oxygen).

Step2: Analyze the slopes

Sample A has the least steep slope among the four samples in the graph. This indicates that it has the lowest rate of oxygen consumption over time, which means it has the lowest BOD and thus the lowest level of organic matter.

Answer:

A