A city has experienced an increase in vehicle traffic in the last few years. During this time, the city has also recorded an increase in air pollution. Which solution should the city choose to best reduce air pollution in the coming years?
A.
Monitor the levels of air pollution during rush hour each day.
B.
Provide more public facilities for the disposal of motor oil used in vehicles.
C.
Encourage using public transportation rather than driving individual cars.
D.
Prohibit all use of motor vehicles on all roads in the city.