Hi,
Best four are to be chosen in every course including hons. If you are doing politics science hons. then your percentage for best four will be serve as your percentage. The criteria for choosing best four is :-
1. One Language subject (core/elective/vocational)
2. The subject in which you want to seek hons. In your case, political science. Otherwise marks will be deducted.
3. Two other elective subjects.