The Battle of Ten Kings was fought in the Early Vedic Period on the banks of the Parushni river. During the Early Vedic Period, there were numerous conflicts between various tribes and kingdoms. The Battle of Ten Kings was one such conflict where ten tribal kings fought against Sudas, the ruler of the Trtsu dynasty.

Now let`s examine the other options to understand why they are not the correct answers:

Option 1: Sarasvati - The Sarasvati river is regarded as a sacred river in Hinduism, but there is no historical evidence to suggest that the Battle of Ten Kings took place on its banks.

Option 2: Drishadvati - The Drishadvati river is mentioned in the Rigveda, but there is no mention of the Battle of Ten Kings being fought on its banks.

Option 4: Shutudri - The Shutudri river, also known as the Sutlej river, is located in present-day India and Pakistan. While it is an important river in the region, there is no historical evidence to suggest that the Battle of Ten Kings occurred on its banks.

Therefore, the correct answer is option 3: Parushni, as it is the only river mentioned in the context of the Battle of