What are the main energy sources for earth's internal heat engine?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. Radiogenic heat and primordial heat.
The main energy sources for Earth's internal heat engine are primordial heat and radiogenic heat. Primordial heat originates from the planet's formation, including the heat from accretion, differentiation, and gravitational compression. Radiogenic heat is produced by the decay of radioactive isotopes such as uranium, thorium, and potassium within Earth's mantle and crust. These sources contribute to the geothermal gradient and drive processes like mantle convection, volcanic activity, and tectonic movements.