‘Q’ will be the first part of the given sequence as ‘which’ is used in relation to ‘moment comes’ mentioned in the opening part of the sentence. ‘PR’ will follow next and will make a pair together both of them are describing ‘when’ the moment can come. ‘S’ will be the last part of the given sequence as ‘nation long suppressed’ is making a logical phrase together. Hence, QPRS is the correct sequence.Thus, option (a) is correct.