Given a scientific passage and an answer, generate a question for the given answer.

Passage: Great volcanic explosions and glowing red rivers of lava are fascinating. All igneous rock comes from magma or lava. Remember that magma is molten rock that is below Earth's surface. Lava is molten rock at Earth's surface. Answer: magma or lava
Where does all igneous rock come from?

Passage: Frogs and toads are adapted for jumping. Salamanders and newts may walk or swim. Caecilians live in the water or soil and are the only amphibians without legs. Answer: caecilians
What is the only amphibian without legs?

Passage: Thermal energy is the total energy of moving particles of matter. The transfer of thermal energy is called heat. Therefore, a heating system is a system for the transfer of thermal energy. Regardless of the type of heating system in a home, the basic function is the same: to produce thermal energy and transfer it to air throughout the house. Answer: heat
What do you call the transfer of thermal energy?