The correct answer is: c) Braiding and shifting courses.
Excessive silt carried by Assam’s rivers leads to a problem of braiding and shifting courses. This is because the silt deposits on the riverbed, making it shallower. This can cause the river to split into multiple channels, or to change course altogether. This can have a number of negative consequences, such as flooding, erosion, and the loss of land.
Option a) is incorrect because Assam does not have a problem with water scarcity. In fact, the state is home to several major rivers, including the Brahmaputra, the Barak, and the Manas. These rivers provide a vital source of water for irrigation, drinking, and other purposes.
Option b) is incorrect because groundwater contamination is not a major problem in Assam. The state has a number of well-regulated groundwater resources, and the quality of the water is generally good.
Option d) is incorrect because Assam does not have a problem with a lack of aquatic life. The state is home to a diverse range of fish and other aquatic animals. These animals are an important part of the ecosystem, and they play a vital role in the food chain.