Which one of the following rivers marks the western boundary of the Ganga Plains ?

The Ganga Plain is the central part of the Great Northern Plains of India. It extends from the Yamuna River in the west to the Bangladesh border in the east, covering a distance of about 1,400 km. The Yamuna river serves as the western boundary, effectively acting as the water divide between the Ganga system and the Indus system (specifically the Punjab-Haryana plains). To the north, the plain is bounded by the Shiwalik range of the Himalayas, and to the south, it is bounded by the northern edge of the Peninsular Plateau. While the Chambal is a major tributary of the Yamuna, it flows through the Malwa Plateau. The Ghaggar and Luni rivers are located further west in the semi-arid regions of Haryana and Rajasthan, respectively, and do not define the boundary of the Ganga Plains.