Global warming may result in

The statements that are $TRUE$:
$A$. Methane leads to both global warming and photochemical smog.
$B$. Methane is generated from paddy fields.
$C$. Methane is a stronger global warming gas than $CO_2$.
$D$. Methane is a part of reducing smog.
Choose the most appropriate answer from the options given below:

Which of the following statements is incorrect?

Which of the following molecules react with haemoglobin of the blood to produce toxic effect?

The relative contribution of $O_3$,$N_2O$,and $H_2O$ to global warming is in the ratio of ......

$BOD$ stands for