Why is Earth's outer core hotter than Earth’s oceanic crust?

Question

Earth’s oceanic crust is denser than Earth’s outer core is.
Earth’s oceanic crust has lava flowing from the mantle.
Earth’s outer core has a composition of solid iron and nickel.
Earth’s outer core is deeper within Earth than oceanic crust is.

Answer 1

The correct reason why Earth's outer core is hotter than Earth's oceanic crust is:

Earth’s outer core is deeper within Earth than oceanic crust is.

As you go deeper into the Earth, the temperature generally increases due to the immense pressure and the heat generated from the decay of radioactive isotopes, as well as residual heat from the planet's formation. The oceanic crust is much closer to the surface, while the outer core is located about 2,900 kilometers (1,800 miles) beneath the surface, leading to significantly higher temperatures in the outer core.