When addressing a person or thing directly, the proper name or the word which is used to address the listener must be offset from the rest of the sentence, with a comma. In the given sentence, the word 'Sir' is used to address the listener. Hence, it has to be offset from the remaining sentence by a comma.
Option B: The word, 'Sir' is offset from the remaining sentence by a comma and there is no other incorrect punctuation mark. Hence, this option is correct.
Options A and C are incorrect as the word, 'Sir' is not followed by a comma. Further, in option A, both the words, 'Please' and 'Pardon' in the middle of the sentence begin with a capital letter. This is incorrect.
In option D, there is an incorrect (and unnecessary) comma after the phrase, 'please pardon me'. Hence, this option is incorrect.