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?

Let's analyze each pair of literary work and author:

1. Devichandragupta : Bilhana - This pair is incorrectly matched. 'Devichandragupta' is a Sanskrit play attributed to Vishakhadatta, who also wrote 'Mudrarakshasa'. Bilhana was a Kashmiri poet who wrote 'Vikramankadevacharita', an epic poem on the life of the Chalukya king Vikramaditya VI.

2. Hammira-Mahakavya : Nayachandra Suri - This pair is correctly matched. 'Hammira-Mahakavya' is a historical epic poem (Mahakavya) about the Chahamana king Hammira-deva of Ranthambore, composed by the Jain scholar Nayachandra Suri.

3. Milinda-panha : Nagarjuna - This pair is incorrectly matched. 'Milinda-panha' (Questions of Milinda) is an important Buddhist text, which records a dialogue between the Indo-Greek King Menander I (Milinda) and the Buddhist monk Nagasena. Nagarjuna was a prominent Buddhist philosopher and the founder of the Madhyamaka school of Mahayana Buddhism, who lived several centuries after Nagasena.

4. Nitivakyamrita : Somadeva Suri - This pair is correctly matched. 'Nitivakyamrita' is a significant text on polity and ethics, composed by the Jain Acharya Somadeva Suri in the 10th century.

Therefore, only two pairs (2 and 4) are correctly matched.