Acid rain is caused by,or recent reports of acid rain in some industrial cities are due to the effect of atmospheric pollution by:

• A
  Excessive release of $CO_2$ by burning of fuels like wood and charcoal,cutting of forests and increased animal population.
• B
  Excessive release of $NO_2$ and $SO_2$ in the atmosphere by burning of fossil fuels.
• C
  Excessive release of $NH_3$ by industrial plants and coal gas.
• D
  Excessive release of $CO$ in the atmosphere by incomplete combustion of coke,charcoal and other carbonaceous fuels in the paucity of oxygen.