The correct answer is: a) Rivers.
Bihar is a landlocked state in eastern India. It is bordered by Nepal to the north, Uttar Pradesh to the west, Jharkhand to the south, and West Bengal to the east. The state has a population of over 100 million people, making it the third most populous state in India.
The main rivers in Bihar are the Ganges, the Son, and the Gandak. These rivers provide a vital source of water for irrigation, drinking, and fishing. Many communities in Bihar traditionally depend on fishing for their livelihoods.
Coastal areas are not a major source of fishing in Bihar. The state is located far from the coast, and there are no major ports or fishing villages.
Wetlands are also not a major source of fishing in Bihar. The state has a few small wetlands, but they are not as important for fishing as the rivers.
Mountain streams are also not a major source of fishing in Bihar. The state has a few mountain ranges, but the streams are not as productive for fishing as the rivers.
In conclusion, the correct answer is: a) Rivers.