Confused in Subject Selection .
 

I am civil Engineer. I want to appear in CSS 2020
But I am really confused in optionals selection
1. I want to opt Physics but reading very upsetting reviews about it here on forum .. made me confuse
2. Environmental sciences or Gender Studies.
Tips and strategies to cover above mention subjects.
My selection of optionals for now:
1. IR
2. Physics or ( IL & European History )
3. Environmental science or Gender Studies
4. Sociology
Please Guide me .
All suggestions are welcome