UngeheuerLich
Legend
Yes. Logically "or" is the correct choice here. In natural language "and" would probably be the better choice.I think this is because you can only apply proficiency from one skill at a time, so you can't add your Arcana and Nature proficiency to the same roll.
(This does mean that if you wanted to minimax for Arcana checks, don't play a single-class wizard)
Is the windows open or closed? Yes.
Is it open and closed? Only if it is broken.