Which among the following pairs consists only of herbicides?

Use of chlorofluorocarbons is not encouraged because

Observe the following statements:
Statement-$I$: The carbon-containing components of photochemical smog are acrolein,methanal,and $PAN$.
Statement-$II$: The number of greenhouse gases in the list given below is $5$: $CH_4, CO_2, NO, H_2O_{(l)}, H_2O_{(g)}, O_2, O_3$.
The correct answer is:

The concentration of dissolved oxygen $(DO)$ in cold water can go up to ......... $ppm$.

Which pollutant poses a threat to the $Taj$ $Mahal$?

$A$ farmer is using pesticides in his field. He uses the produce from his field as food for fish. He is told that the fish are not fit for human consumption because large amounts of pesticides were found in the fish cells. How is this possible? Explain.