Which region of the Earth is molten and primarily liquid?

• A. Crust
• B. Outer Core
• C. Inner Core
• D. Mantle

Answer: (B)

The outer core is the region of the Earth that is molten and primarily liquid. It lies beneath the mantle and above the inner core and is composed mainly of iron and nickel. The semi-fluid state of the outer core is essential for the generation of the Earth's magnetic field through the movement of molten metals.

In contrast, the crust is the outermost solid layer of the Earth, and it is composed of solid rock. The mantle, while it has partially molten areas, is mostly solid with some regions capable of flowing over geological timescales. The inner core, on the other hand, is solid despite being under immense pressure and temperature; its composition is similar to that of the outer core but in a solid state. Thus, the outer core's characteristics distinctly define it as the molten and primarily liquid region of the Earth's structure.