Which river is known as the “Sorrow of Bihar”?

The correct option is Kosi.

The Kosi River is known as the "Sorrow of Bihar".

Reasoning & Background:

1. Frequent Flooding: The Kosi River originates in the Himalayas and flows through Nepal before entering the plains of Bihar, India. Due to large amounts of silt and sediment carried down from the mountains, the riverbed rises constantly.

2. Course Shifting: Over the last two centuries, the river has shifted its course laterally by over 120 km, causing widespread destruction of fertile agricultural land, human settlements, and loss of life during the monsoon season.

3. Because of these devastating recurrent floods and unpredictable changes in its flow, it has earned the epithet "Sorrow of Bihar".