Which of the following statements regarding Earth's internal structure is/are correct ? 1. The oceanic crust is heavier than the continental crust. 2. Most of the Earth's internal heat is contained within the mantle. 3. Large convective cells in the crust circulate heat and drive plate-tectonic processes. Select the answer using the code given below :

Statement 1 is correct: The oceanic crust is denser (heavier) than the continental crust. It is primarily composed of basaltic rocks with an average density of about 3.0 g/cm³, whereas the continental crust consists of lighter granitic rocks with a density of approximately 2.7 g/cm³.

Statement 2 is correct: The mantle makes up about 84% of Earth's total volume. Because of its massive size compared to the crust and the core, it contains the largest portion of the Earth's internal heat, which is generated by radioactive decay and primordial heat.

Statement 3 is incorrect: Convection cells that drive plate tectonics operate within the mantle (specifically the asthenosphere), not the crust. The crust is the rigid outermost layer that is moved by the underlying convective currents in the mantle.