professional mark

That is what the examiner's report indicates - a conclusion isn't really something that a briefing note would have.

but why do all past paper with briefing note has conclusion ? some says we need while the other says we don't need .... i'm really confused sorry Kim

In the same vein - why do model answers have more than one sentence of introduction? I know it's confusing and I sigh too. This would be a good question for you to ask if you can attend ACCA's next FREE webinar on 22 May - you can register here https://www.accaglobal.com/ie/en/student/exam-support-resources/professional-exams-study-resources/p7.html