Logic Puzzle

You must preform action D unless condition A or B or C is true. Condition A is false. Condition B is true. Condition C is false. Must you perform action D?

I met with not the landlord, but the landlord's partner and head contractor and ended arguing over the building code. Ever argued building codes with a Scottish contractor with 30+ years experience who happens to be wrong? There is just no way for that to go well.

This blasted window thing is not over yet. I'm angry and frustrated.