The correct answer is (b).
Assam is a state in north-eastern India. It is bordered by Bhutan to the north, Arunachal Pradesh to the north-east, Nagaland to the east, Manipur to the south-east, Mizoram to the south, Tripura to the south-west, Meghalaya to the west, and Bangladesh to the south-west and west. The state capital is Dispur.
The geological formation of Assam is primarily related to sedimentation from rivers. The Brahmaputra River, the largest river in India, flows through the state. The river has deposited a large amount of sediment over time, which has formed the Brahmaputra Valley. The valley is a fertile plain that is home to a large population.
The other options are incorrect. Volcanic activity is not a major factor in the geological formation of Assam. Glacial movements have also not had a significant impact on the state’s geology. Coastal erosion is not a major problem in Assam, as the state is not located on the coast.
In conclusion, the geological formation of Assam is primarily related to sedimentation from rivers. The Brahmaputra River has deposited a large amount of sediment over time, which has formed the Brahmaputra Valley. The valley is a fertile plain that is home to a large population.