Question

Rain becomes acidic (a) because excess of carbon dioxide present in air get dissolved in rain drops to form carbonic acid. (b) oxides of nitrogen and sulfur present in air dissolve to form respective acids (c) both the above are correct​

Answer 1

acid rain is observed when its ph goes down below 5. This happens mainly due to the mixing of carbon dioxide in rain which results in the formation of carbonic acid. Even sulpur can mix and form suphuric acid which is relatively dangerous. nitrogen can form its acid mixing with water. These wont be highly dangerous as far their relative amount is less. But at time they can even burn the skin when once they fall. Usually plants face threats due to this. Agriculture in acid rain affected regions are really poor. 

so the answer is c