The correct answer is: a) Sedimentary rocks.
Sedimentary rocks are the most common type of rock in Arunachal Pradesh. They are formed from the accumulation of sediments, which are pieces of other rocks that have been broken down by weathering and erosion. Sediments can be transported by water, wind, or ice, and they can be deposited in a variety of environments, such as rivers, lakes, oceans, and deserts. Over time, the sediments are buried and compacted, and they are eventually cemented together to form sedimentary rocks.
Igneous rocks are formed when molten rock, or magma, cools and solidifies. Magma can be found beneath the Earth’s surface, or it can erupt onto the surface as lava. When magma cools slowly, it forms large, coarse-grained igneous rocks. When magma cools quickly, it forms small, fine-grained igneous rocks.
Metamorphic rocks are formed when existing rocks are subjected to heat and pressure. The heat and pressure can cause the rocks to change their shape, size, and composition. Metamorphic rocks can be formed in a variety of environments, such as deep within the Earth’s crust, near volcanoes, and in mountain ranges.
Volcanic rocks are formed when magma erupts onto the surface of the Earth as lava. Lava can flow out of a volcano or it can be ejected into the air. When lava cools, it forms volcanic rocks. Volcanic rocks can be found in a variety of shapes and sizes, and they can be made up of a variety of minerals.
The geological formations in Arunachal Pradesh are predominantly sedimentary rocks. This is because the state is located in a region that was once covered by a shallow sea. The sediments that were deposited in this sea eventually formed sedimentary rocks.