Understanding Earth's Layers
The Earth is composed of several distinct layers, each with unique characteristics and functions. The outermost layer is known as the crust.
What is the Crust?
- The crust is the Earth’s outer shell, forming a thin layer compared to the other layers beneath it.
- It varies in thickness from about 5 kilometers (3 miles) under the oceans (oceanic crust) to about 30-50 kilometers (19-31 miles) under continental landmasses (continental crust).
Composition of the Crust
- The crust is primarily composed of rocks and minerals such as granite and basalt.
- It contains essential elements like silicon, oxygen, aluminum, iron, calcium, sodium, potassium, and magnesium.
Importance of the Crust
- The crust is where we live, and it supports ecosystems, human activities, and agriculture.
- It is also the layer where geological phenomena occur, such as earthquakes and volcanic eruptions.
Distinction from Other Layers
- Beneath the crust lies the mantle, a thick layer of semi-solid rock, while the core is composed mainly of iron and nickel.
- The crust is much cooler than the mantle and core, which are hotter and under higher pressure.
In summary, the correct answer to the question about the outermost layer of the Earth is indeed option 'A', the crust. This layer is crucial for supporting life and shaping the planet's surface.

It's answer is crust