'R' will be the first part as the phrase 'believe even now' pairs it with the opening part of the given sequence which says, "I believed then". 'P' will come next as it continues the aspect of what one believed then and now. It will be followed by 'S' because 'amount of work' is used in relation to 'no matter' in P. 'Q' will obviously form the last part of the given order. Hence, RPSQ is the correct sequence. Thus, option (d) is correct.