The Brahmaputra River, one of the major water bodies in India, is known for its tributaries that contribute to its massive flow.

Option 1: The Ghaggar River is primarily situated in the states of Haryana and Rajasthan in western India. It`s not a tributary of the Brahmaputra.

Option 2: The Mahi River runs through Central India, traversing the states of Madhya Pradesh and Rajasthan, eventually ending in Gujarat - quite far from the course of the Brahmaputra.

Option 3: The Kosi River is a tributary, but of the Ganges River, not the Brahmaputra. It primarily flows through Bihar, further north and west than where the Brahmaputra is located.

Option 4: The Manas River, named after the serpent goddess Manasa, originates in the Himalayas of Bhutan and enters India in Assam, making it a tributary of the Brahmaputra River. Thus, option 4 is the correct answer.