The Biological Oxygen Demand $(BOD)$ of water is:

Given below are two statements:
Statement $I:$ In a scrubber,the exhaust from the thermal plant is passed through a spray of water or lime to remove gases like $SO_2$.
Statement $II:$ Particulate matter $(PM\,2.5)$ cannot be removed by a scrubber but can be removed by an electrostatic precipitator.
In the light of the above statements,choose the most appropriate answer from the options given below:

$A$: Water hyacinth is one of the most invasive weeds.
$R$: It increases the dissolved oxygen of water.

Which of the following is absent in polluted water?

$CO$ (Carbon Monoxide) is harmful because........

What is Agent Orange?