The correct answer is: The Brahmaputra system.
Manipur is drained by several rivers belonging to two major river systems: the Brahmaputra system and the Barak River system. The Brahmaputra River is the largest river in the Indian subcontinent and the ninth largest river in the world. It originates in the Himalayas in Tibet and flows through India and Bangladesh before emptying into the Bay of Bengal. The Barak River is the second largest river in Manipur and originates in the Manipur Hills. It flows through the state and joins the Brahmaputra River in Assam.
The other options are incorrect because they do not drain Manipur. The Chindwin-Irrawaddy system is a river system in Myanmar. The Ganga system is a river system in India. The Mahanadi system is a river system in India.
The Brahmaputra River is a major source of water for irrigation, drinking water, and hydroelectric power in Manipur. The river is also a popular tourist destination.