Question

Select the correct option w.r.t. the given graph.

• A. Least polluted area –B
  Moderately polluted area – A
  Highly polluted areas – C, D
• B. Least polluted area –C
  Moderately polluted area – B,D
  Highly polluted areas – A
• C. Least polluted area –A
  Moderately polluted area – B,D
  Highly polluted areas – C
• D. Least polluted area –C
  Moderately polluted area – A,B
  Highly polluted areas – D

Answer 1

The correct option is C Least polluted area –A

Moderately polluted area – B,D
Highly polluted areas – C
BOD (Biochemical Oxygen Demand) is the amount of dissolved oxygen needed by aerobic organisms in a water body to break down organic material. The measure of BOD is directly proportional to the pollution level of the area.

$\begin{array}{cc}\text{Area}& \text{BOD}\\ \text{A}& \text{< 1000~mg/L}\\ \text{B}& \text{2000-2500~mg/L}\\ \text{C}& \text{4000~mg/L}\\ \text{D}& \text{2000 mg/L}\end{array}$


Thus, according to the given data, A is the least polluted area, B and D are moderately polluted areas and C is a highly polluted area.