Correct Option
The correct option is 2 and 3 only.
Explanation
The internal structure of the Earth is divided into concentric layers based on chemical and physical properties: the Crust, the Mantle, and the Core. The Crust forms the thin, outermost solid shell of the planet.
Statement-wise Analysis
- Statement 1 is Incorrect: The Crust is the outermost solid part of the Earth. The innermost part of the Earth is the Core (specifically the Inner Core).
- Statement 2 is Correct: The Crust is brittle in nature. Under stress, it tends to fracture rather than flow, which is why faults develop and earthquakes occur within this layer. In contrast, the deeper mantle behaves more plastically over geological timescales.
- Statement 3 is Correct: The thickness of the crust varies significantly between oceanic and continental regions. The oceanic crust is thinner (averaging 5 km), whereas the continental crust is much thicker (averaging around 30 km and reaching up to 70 km in major mountain systems like the Himalayas).
Key Takeaway: The Crust is the Earth's outermost, brittle layer, characterized by distinct thickness variations where the continental crust is significantly thicker than the oceanic crust.