Question: Earth's interior heat is the engine that powers?
Answer: mountain building
earthquakes
plate tectonics
volcanic activity
plate tectonics, volcanic activity, earthquakes, and mountain building
Disambiguated questions and answers: question: Earth's interior heat is the engine that powers what processes?
Earth's interior heat is the engine that powers what theory of movement?
answer: geological
plate techtonics
Natural Questions answer: most geological processes (from the Wikipedia article "Earth's internal heat budget")