lithosphere and mesosphere inner core and outer core outer core and mantle mantle and crust
I am hesitating between 4 options to answer the following question, which option should I choose?
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?
Possibilities:
- lithosphere and mesosphere
- inner core and outer core
- outer core and mantle
- mantle and crust

inner core and outer core