Correct Answer: Nitrogen oxide and sulphur dioxide

Solution : The correct answer is Nitrogen oxide and sulphur dioxide.

Acid rain is caused by the Nitrogen oxide and sulphur dioxide pollution because of which these gases dissolve with water vapours in the clouds and forms nitric acid and sulphuric acid respectively, which falls on the ground with the rain. Usually it has a pH of 4.0 and it is lethal for human health, plant health and infrastructure. It is also known as transboundary pollution because these gases are released somewhere else, but they are carried with the winds which leads to their deposition in some other place.