Which of the following has resulted in reduction of Delhi's pollution?

Compressed natural gas in public transport

According to the State of Global Air report, Delhi has been ranked as the most polluted city in the world, followed by Kolkata, in terms of PM 2.5 concentrations. The government has taken various measures to control this. It includes odd even policy, the odd-even system of the Delhi government allows private vehicles to be driven only on alternating days, depending on the last digit of their number plate. Apart from this, government has asked people to buy CNG vehicles to reduce the level of pollution in the country.