Based on the search results, the correctly matched pairs are:
- I. Asmaka | Godavari: Correct, as the Asmaka region is associated with the Godavari River.
- IV. Kosala | Sarayu: Correct, as the Kosala region is associated with the Sarayu River.
The other pairs are incorrect:
- II. Kamboja | Vipas: Incorrect, as there is no evidence linking the Kamboja region with the Vipas (Beas) River.
- III. Avanti | Mahanadi: Incorrect, as the Avanti region is associated with the Sipra and Narmada rivers, not the Mahanadi.