‘S’ will be the first part of the given sequence as it talks about one of the common modes in solar energy utilisation, that is, solar thermal conversion. ‘Q’ will follow next as it talks about the commercialisation of large number of applications. ‘P’ will follow next as ‘these’ is used in the context of ‘large number of applications’ in Q. ‘R’ will follow next as it further talks about the ‘efforts’. Hence, SQPR is the correct sequence. Thus, option (c) is correct.