Which of the following statements regarding water quality indicators are correct? 1. Dissolved Oxygen (DO) content below 4.0 mg/L is considered highly polluted and unsuitable for aquatic life. 2. Biochemical Oxygen Demand (BOD) measures the amount of oxygen required to oxidise both biodegradable and nonbiodegradable matter in water. 3. Chemical Oxygen Demand (COD) is considered a better measure than BOD for total pollution load, as it accounts for both biodegradable and nonbiodegradable organic matter. 4. Higher BOD values indicate higher dissolved oxygen content in water. Select the answer using the code given below: |ForumIAS

[A] 1 and 3 only

[B] 1, 2 and 3 only

[C] 2, 3 and 4 only

[D] 1 and 4 only

Answer: A

Notes:

Explanation:

DO below 4.0 mg/L is considered highly polluted and harmful for aquatic life.
BOD measures oxygen needed to decompose biodegradable matter only, not nonbiodegradable matter.
COD includes oxygen demand for both biodegradable and nonbiodegradable organic matter, making it a more comprehensive pollution measure.
Higher BOD means lower DO content, as more oxygen is consumed by decomposition.

Source: Environment (N.C.E.R.T)