'Q' will be the first part as 'poet' is used in relation to 'Wordsworth' in the opening part of the given sequence. 'P' will follow next as 'on the hours' is used in relation to 'school days' in Q. 'R' will come next as it states the activities done by him at night when he was out of school. It will then be followed by 'S' as it states that he was a night walker and thus this sentence pairs with S6 which makes it clear that being a night walker, his poetry owes much to the night. Hence, QPRS is the correct sequence. Thus, option (a) is correct.