Please choose the correct answer to the question: Some of the thermal structure of Earth is the result of a combination of chemical composition, temperature, and pressure. Which is a boundary that best demonstrates a contact point between layers having relatively the same temperature and chemical composition?

Answer1: lithosphere and mesosphere Answer2: inner core and outer core Answer3: outer core and mantle Answer4: mantle and crust

Answer format: answer1/answer2/answer3/answer4
Answer: answer2