The following items in this question consists of a sentence, the parts of which have been jumbled. These parts have been labelled P, Q, R and S. Given below each sentence are four sequences namely (a), (b), (c) and (d). You are required to re-arrange the jumbled parts of the sentence correctly and mark your response accordingly.

(P) ecology is protected and aquatic life thrives
(Q) we need to utilize the resources of water
(R) for different purposes while
(S) ensuring that its natural

The correct sequence should be :

Options