Each of the following questions consists of a sentence, parts of which have been jumbled. These parts have been labeled as P, Q, R, and S. Given below each sentence are four sequences, namely (a), (b), (c), and (d). Rearrange the jumbled parts of the sentence and mark your response accordingly.

stations contain electrical generators(P)/ electrical power generating(Q)/  which have to be rotated(R)/ at a uniform speed(S)