Final answer:
The Earth's outer core is hotter than its oceanic crust because the outer core is deeper within the Earth and is under greater pressure and temperature than the crust.
Step-by-step explanation:
The reason why Earth's outer core is hotter than Earth's oceanic crust is due to the position of these layers within the Earth's structure. The correct answer to the student's question is d) Outer core is deeper within Earth than oceanic crust is.
Earth's core, mantle, and crust, are defined by their chemical compositions with the core mainly consisting of iron and nickel. The Earth's inner core is solid, but the outer core surrounding it is liquid. This liquid outer core is extremely hot due to the high pressure and the radioactive decay of elements. Meanwhile, the Earth's crust, which includes the oceanic crust, is the outermost layer and much cooler in comparison, as it is in direct contact with the ocean water and atmosphere.
The oceanic crust is approximately 6 kilometers thick, composed of basalt, and lies mostly under the oceans. It is much less dense than the core and does not have the same level of heat-producing materials or geothermal gradient found deeper within the Earth.