Which of the following statements are correct?
$A$. Ocean is a sink for $CO_2$.
$B$. Greenhouse effect causes lowering of the temperature of the earth's surface.
$C$. To control $CO$ emission by automobiles,usually catalytic converters are fitted into exhaust pipes.
$D$. $H_2SO_4$,herbicides,and insecticides form mist.

• A
  $C$ and $D$
• B
  $A$ and $B$
• C
  $B$ and $D$
• D
  $A$ and $C$