Which of the following statements is correct?

a- Environmental pollution results from the release of substances and energy from waste products of human activities.
b- Different types of pollution are classified on the basis of the medium through which pollutants are transported and diffused.

Both statements are correct.

Environmental pollution results from ‘the release of substances and energy from waste products of human activities. There are many types of pollution. They are classified on the basis of the medium through which pollutants are transported and diffused. Pollution can be classified into (i) air pollution, (ii) water pollution, (iii) land pollution and (iv) noise pollution.