Carbon monoxide is a major pollutant of

For the control of air pollution in Delhi, all buses of Delhi were converted to run on $A$ by the end of $B$ as per the directives of the $C$. Complete the given statement by choosing appropriate options for $A-C$.

Consider the following statements about a scrubber:
$I.$ It is used to remove gases like sulphur dioxide from industrial exhaust.
$II.$ In a scrubber,the exhaust is passed through a spray of water or lime.
$III.$ Water dissolves gases and lime reacts with sulphur dioxide to form a precipitate of calcium sulphate or calcium sulphide.
Which of the statements given above are correct?

By the end of $2002$, which step was completed in Delhi to reduce vehicular pollution?

Acid rain is the secondary effect of

Which of the following is a major air pollutant?