The correct option is C Planting more trees
Air pollution can be reduced by:
∙ Using a bicycle for transportation - This reduces the emission of harmful gases into air.
∙ Reducing the use of firecrackers - This reduces the emission of thick smoke which pollutes the air.
∙ Planting more trees - Trees clean the air by taking in carbon dioxide and releasing oxygen during respiration.
But, burning of garbage releases a large amount of smoke which leads to air pollution.