The correct answer is: a) Ancient volcanic rocks.
Nagaland is a state in northeastern India. It is bordered by Assam to the north, Manipur to the west, and Myanmar to the east and south. The state has a population of over 1.9 million people, and its capital is Kohima.
The geological formation of Nagaland is primarily composed of ancient volcanic rocks. These rocks were formed when the Indian subcontinent collided with the Eurasian Plate millions of years ago. The collision caused the Indian Plate to buckle and fold, and the resulting mountains were eroded over time to form the present-day landscape of Nagaland.
The ancient volcanic rocks of Nagaland are a valuable resource for the state. They are used in the construction industry, and they are also a source of minerals such as coal and limestone.
The other options are incorrect because:
- Sedimentary rocks are formed when sediments, such as sand and mud, are deposited over time and compacted. Nagaland does not have a lot of sedimentary rocks.
- Metamorphic rocks are formed when existing rocks are subjected to heat and pressure. Nagaland does not have a lot of metamorphic rocks.
- Igneous rocks are formed when magma or lava cools and solidifies. Nagaland does have some igneous rocks, but they are not the primary type of rock in the state.