The given sentences describe a scene where the narrator repeatedly hits the snooze of an alarm (thrice) and finally realises it is too late to have breakfast and leaves without having the same. The word, "it" in the sentences refers to the alarm.
Sentence S1 talks about the first time the alarm goes off and the narrator hits the snooze.
Sentence P begins with the word, "then". This tells us that it talks about a subsequent time that the alarm goes off and is snoozed. However, we do not know if this is the second or third time. Sentence R mentions that "it goes off the third time". From this, we know that sentence P refers to the second alarm; Sentence R refers to the third alarm. Hence, S1 (first alarm) is followed by P (second alarm) and then R (third alarm). The only sentence remaining is Q (which begins with the word, "finally"). Hence, the correct sequence is S1, P, R and Q. The only option which indicates this is option A, which is the correct answer.
Options B and D: In both these options, sentence R follows S1. This sequence is incorrect. Sentence R talks about the third time the alarm goes off. Sentence S1 talks about the first time the alarm goes off. Hence, R cannot immediately follow S1 (without mentioning the second alarm). Hence this option is incorrect.
Option C: Here, Q follows S1. The word, "finally" in sentence Q tell us that this step happens much later, after hitting the snooze button two more times (which are explained in sentences P and R). Hence, Q cannot immediately follow the first sentence, S1. Hence, this option is incorrect.