6. With reference to ancient Indian History, consider the following pairs:
Literary work | Author

1. Devichandragupta | Bilhana

2. Hammira-Mahakavya | Nayachandra Suri

3. Milinda-panha | Nagarjuna

4. Nitivakyamrita | Somadeva Suri

How many of the above pairs are correctly matched?