What is one of the major parts in Earth's outer crust layer called?

The correct answer is "Plate" because Earth's outer crust is composed of several tectonic plates, which are large rigid pieces that fit together like a jigsaw puzzle. These plates are crucial elements of the lithosphere, the rigid outer layer of the Earth, and they float on the semi-fluid asthenosphere beneath them. The movement of these plates is responsible for many geological processes, including earthquakes, volcanic activity, and the formation of mountains.

Each plate can interact with others through various types of boundaries (divergent, convergent, and transform), leading to significant geological phenomena. Understanding the concept of tectonic plates is fundamental in earth science as it explains the dynamic nature of Earth's surface and its geological history.

The other options, while related to geological terminology, do not specifically refer to the large, rigid sections that make up Earth's outer crust. "Layer" is a general term that could refer to any distinct stratum in geological contexts, "Shell" typically refers to a surrounding layer or structure but is not specific to geology, and "Stratum" denotes a specific layer of rock or soil, but not in the context of the crust's major parts.