💡 Detailed Explanation
"～末（に）" indicates a final result after a long period of time, effort, or various circumstances. Here, it means "after the process of a long discussion, a decision was finally made." "～あげくに" is inappropriate as it usually implies a negative outcome. "～以上は" means "now that..." and is used to express determination or obligation. "～上で" means "after doing X," but "末に" better expresses the nuance of a long time or struggle.