‘R’ will be the first part of the given sequence as ‘the followingyear’ shows that the reference is made in succession to the year ‘1818’ mentioned in the opening part of the given passage. ‘P’ will come next as the pronoun ‘she’ is used in the context of ‘Sarah Bush Johnson’. ‘S’ will come next as thephrase ‘these books’ is used in the context of ‘several books’ in ‘P’. ‘Q’ will follow next as the phrase ‘this moral and intellectual debt’ is used in the context of ‘a mass of knowledge’ in ‘S’. Hence, RPSQ is the correct sequence. Thus, option (c) is correct.