Don't be hurry during selection of optional subjects. Accounting and auditing is one of the scoring subject as compare to other. Keep in mind two things if you opt this subject; 1) You have strong background for this subject 2) You must have interest and aptitude towards this subject.
As far as IR is concerned, it gain importance after the revision of syllabus. Although it is very lengthy and difficult subject, but it can help you in other subjects as well, like in essay, Pakistan affair and current affair.
Finally my suggestion is go for accounting if you have strong background, otherwise IR is best option for you.

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"Allah is sufficient for us;an excellent guardian is He!