What is the primary composition of the Earth's core?

The primary composition of the Earth's core is predominantly iron, which is supported by extensive geological and geophysical evidence. The core is divided into two parts: the outer core, which is liquid, and the inner core, which is solid. Both layers are primarily composed of iron, along with smaller amounts of nickel and other lighter elements.

The high density of the core suggests a metallic composition, and seismic wave studies indicate that the outer core is liquid because seismic waves travel slower through it compared to the solid inner core. This understanding aligns with the properties of iron, which remains solid at high pressures and temperatures encountered in the inner core.

Other materials mentioned in the options, like silicate rock, granite, and basalt, are primarily found in the Earth's crust and mantle, rather than the core. Therefore, recognizing that the core's composition is rooted in metallic elements, particularly iron, is crucial for understanding the Earth's internal structure.