‘P’ will be the first part of the given sequence as it contains the words, ‘those students’ which refers back to the given statement, ‘The principal said that’. ‘R’ will come next as it tells us about the quality of the students talked about in ‘P’. ‘S’ will follow logically as it contains the object on which the action takes place, that is, ‘identity cards’. ‘Q’ will follow logically at as the end as it informs us about the action taken if the conditions in the previous words are not fulfilled. So, PRSQ becomes the right sequence of words. Hence, option (c) is correct.