The correct answer is A (Automobiles).
Particulate matter is a complex mixture of extremely small particles and liquid droplets.
One of the major components of particulate matter is sulphate usually coming from sulphur dioxide found in exhaust fumes that have been produced by automobiles . Other components are nitrates , ammonia, sodium chloride and black carbon.
Other components of particulate matter come from dust, soot, smoke, industrial emissions.
Particulate matter is one of the most common contributor to air pollution.
