✅ I. Asmaka : Godavari

• Asmaka (or Assaka) was a Mahajanapada located in the Deccan region on the banks of the Godavari river. This pair is correctly matched.

❌ II. Kamboja : Vipas

• Kamboja was in the north-western part of the Indian subcontinent (around Afghanistan and Tajikistan). The river Vipas (Beas) flows in Punjab, so this pair is incorrectly matched.

❌ III. Avanti : Mahanadi

• Avanti was in western Madhya Pradesh with Ujjain as its capital. The main river there was the Kshipra, not the Mahanadi, so this pair is incorrect.

✅ IV. Kosala : Sarayu

• Kosala was a Mahajanapada in present-day eastern Uttar Pradesh, through which the Sarayu river flows. This pair is correct.