‘R’ will be the first part of the given sequence as it talks about the coming of industrial revolution( much later than early man learning about producing heat by burning wood) based on production of steam by burning coal. ‘P’ will come next as the transition word ‘then’ shows that ‘steam’ was later used for producing electricity. ‘Q’ will come next because it tells about the use of oil and ‘gas’. ‘S’ will pair with ‘S6’ as ‘S’ says that gases are not renewable and S6 gives the reason for same, that is, they cannot be replaced. Hence, RPQS is the right sequence. Thus, option (c) is correct.