Important rivers in Meghalaya include the:

The correct answer is: a) Brahmaputra and Umngot.

The Brahmaputra is the largest river in Meghalaya, flowing through the state from north to south. It is the main source of water for the state and is used for irrigation, drinking water, and hydroelectric power generation. The Umngot is a tributary of the Brahmaputra and is known for its clear water and white sand beaches. It is a popular tourist destination.

The Ganges and Yamuna are rivers in India, while the Amazon and Nile are rivers in South America and Africa, respectively. The Mississippi and Missouri are rivers in the United States. None of these rivers flow through Meghalaya.