Use
of public transport system instead of private vehicles decreases the
pollution as many people use only one vehicle which consume less fuel.It decreases the fuel consumption and pollution. Hence option B is correct.
Natural gas is best to use as fuel because it produces less pollution and more efficiency.Less quantity is needed for more work. Hence option D is correct.
Deforestation
is decrease in number of trees in forest so this leads to in decrease
the photosynthesis process which in turn increases the pollution. Hence option A is correct.