The correct answer is (d), Padma.
The Brahmaputra is a major river in Asia, flowing through China, India, and Bangladesh. It is the second-longest river in India, after the Ganges, and the ninth-longest river in the world. The Brahmaputra is a major source of water for irrigation and drinking water for millions of people in the region. It is also a major transportation route.
The Manas, Subansiri, and Lohit are all tributaries of the Brahmaputra. The Padma is a tributary of the Ganges. It flows through Bangladesh and joins the Ganges to form the Meghna River.
The Padma is not a tributary of the Brahmaputra because it flows into the Ganges. The other three rivers, the Manas, Subansiri, and Lohit, all flow into the Brahmaputra.