Your question is Bulb and Switches Once. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are in a sealed room with one bulb and three switches (a, b, c) outside. You can enter the room only once and cannot see inside. How do you confirm which switch controls the bulb?