Match the parts of sentences in column A, B and C to write four complete sentences.

Column A	Column B	Column C
(a) Air pollution	(i) are	(i) from the vehicles is the main cause of it
(b) There	(ii) must be taken	ii) to control this pollution
(c) Black smoke which	(iii) is	(iii) a number of reasons behind this pollution
(d) Immediate steps	(iv) is emitted	(iv) the most dangerous form of pollution