The correct answer is: A. Dangri
The Dangri River is a tributary of the Ghaggar River. It originates in the Shivalik Hills of Himachal Pradesh and flows through the states of Haryana and Rajasthan. The Dangri River joins the Ghaggar River near the town of Suratgarh in Rajasthan.
The Kaushalya River is a tributary of the Yamuna River. It originates in the Shivalik Hills of Uttarakhand and flows through the states of Uttar Pradesh and Haryana. The Kaushalya River joins the Yamuna River near the town of Panipat in Haryana.
The Yamuna River is a tributary of the Ganges River. It originates in the Yamunotri Glacier in the Garhwal Himalayas of Uttarakhand. The Yamuna River flows through the states of Uttarakhand, Himachal Pradesh, Haryana, Delhi, and Uttar Pradesh. The Yamuna River joins the Ganges River near the town of Allahabad in Uttar Pradesh.
The Saraswati River is a mythical river in India. It is said to have originated in the Himalayas and flowed through the plains of northern India. The Saraswati River is now believed to be extinct, but it is still an important river in Hindu mythology.
The Dangri River is the only river among the given options that is a tributary of the Ghaggar River. The other options are tributaries of other rivers.