AFOQT Practice Test

The main layers of the Earth are categorized into the crust, mantle, outer core, and inner core. The correct choice outlines the fundamental internal structure of the Earth, highlighting the distinct layers based on their chemical and physical properties. The crust is the outermost layer where we live, primarily composed of solid rock. Beneath the crust lies the mantle, which is semi-solid and extends to a significant depth, allowing for convection currents that drive plate tectonics. The outer core is a liquid layer composed mainly of iron and nickel, which generates the Earth's magnetic field through its movement. Finally, the inner core is solid due to the extreme pressure, despite its high temperature. The other options present various classifications of Earth’s features, such as atmospheric and ecological layers, but they do not accurately represent the stratification of the Earth’s internal layers. The focus should be on the internally recognized geological layers, which make option A the most relevant and scientifically accepted definition.