Assalam-o-Alaikum
Hope seniors you are doing well. I am highly confused about my optional subjects so i humbly request you to give me your valuable suggestions and guidance. I have recently completed my bs (hons) in biotechnology and want to appear in css 2020. As i have a little time to prepare for it, have no guidance and not able to pay for expensive academies so i am very confused and worried.
I selected these optionals:
international relations
European history
environmental sciences
international law
governance and public policies

plz plz guide me about my optionals as time is too short for preparation and plz also suggest some sources to prepare for compulsory and optionals as i have no social sciences background and have zero knowledge about them.
thanks in advance