An air-conditioning unit, a lamp and an electric fire each take electrical energy from the mains supply. For which one of these devices is all of this energy ultimately passed to the surroundings?
- Aair-conditioning unit ✓, lamp ✓, electric fire ✓
- Bair-conditioning unit ✓, lamp \times, electric fire ✓
- Cair-conditioning unit \times, lamp ✓, electric fire ✓
- Dair-conditioning unit \times, lamp \times, electric fire ✓