Please suggest me which extra subjects to choose in O levels?

[Muhammad Fasih Sher]

So far I have choosen sociology and I want to appear in 1 more subject but I can't choose b/w design and technology, travel and tourism and environmental management. I study in Bloomfield Hall School and I'm in 1st year of O levels which means I wouldn't appear in CIEs this year so I was planning to appear for these extra subjects this year but I don't know the procedure. Any help will be appreciated. JazakAllah