Answer : 3. "यमुना"
Explanation :

The National Green Tribunal (NGT) has directed the Uttar Pradesh Pollution Control Board (UPPCB) to submit an additional report within two weeks on the Hindon River pollution, detailing the action taken against polluting municipal bodies. Hindon, a tributary of Yamuna, extends for 400 km from Saharanpur to Noida. Urban, agricultural and industrial waste has made it one of the most polluted parts of the Ganges basin. In 2015, the CPCB declared it a 'dead river', unfit for bathing.