Question

a bivalent heat pump has two outdoor coils has no compressor has a gas burner has a defrost cycle has electric back - up heat

Explanation:

A bivalent heat - pump combines a heat - pump system with a gas - fired heating system. It has a gas burner to provide additional heat when the heat - pump is not sufficient. It has a compressor (so the option of having no compressor is wrong), not all have two outdoor coils, having a defrost cycle or electric back - up heat is not its defining characteristic.

Answer:

has a gas burner