The story is about a nyctophobiac boy climbing up the stairs to escape his fear. The first sentence would be 'R' which forms a pair with S1 and shows his fearful progressing situation. 'QS' is forming another pair as his actions are stopped for some time and continues afterwards with the 'dying sound' of the clock. 'P' will naturally become the last sentence showing his courage at last to escape his fear through the door. So, correct sequence will be RQSP . Therefore, option (b) is correct.