Read the following passage and answer the questions no. 3 and 4:

Air pollution comes from a wide variety of sources. In Bangladesh poisonous exhaust from industrial plants, brick kilns, old or poorly-serviced vehicles and dust from roads and construction sites are some of the major sources of air. pollution. We can minimise this type of pollution by making less use of motor vehicles and avoiding the use of vehicles older than 20 years. We may also use proper lubricants to lessen the level of emission and pollutants. We can encourage people to use Compressed Natural Gas (CNG) or Liquid Petroleum Gas (LPG) for fuelling their cars. The government may relocate hazardous industries like brick kilns to areas away from human habitations.