If smog density of an area increases, it indicates

$\text{Correct option: }$ C

$\text{Solution: }$ 

$\text{Option (C) }$

$?$The pollutants emitted by the automobile exhaust are nitrogen oxides, gases and fine particles, such as hydrocarbons, ethane, and ethylene.

$?$One of the major steps taken by the Government of India to control pollution includes the amendment of compulsory PUC (Pollution Under control). 

$?$The certification of the petrol driven vehicles should be provided which test carbon monoxide and hydrocarbon emission of the vehicles. 

$?$The smog is a form of air pollution which can reduce the visibility in the atmosphere. 

$?$The increased amount of smog is detected in the state of delhi depicting that the vehicular transportation of the state is not following the PUC norms. 

Hence, the correct option is (C)