It Is Difficult to Directly Observe the Internal Structures of Our

It is difficult to directly observe the internal structures of our Earth, yet we understand many of its physical and chemical properties. One way to understand the chemical properties of the Earth is by calculating the mass and size of the Earth. The average density of the Earth is 5.5 g/cm³; whereas the average density of the continental crust is 2.7 g/cm³ and oceanic crust is 3.3 g/cm³. Which statement best explains the discrepancy between the densities of the Earth's crust versus the overall average?

A) the deeper layers of the Earth are made up of heavier elements such as iron, nickel, and magnesium
B) the sun's effect on the density of the Earth's crust has not been calculated
C) these numbers change with every earthquake occurrence
D) adding the moon's density to the density of the continental and oceanic crusts adds up to Earth's average density