Explanation:

- Option 1: Kalinga War

- ?? Correct Answer

- Emperor Ashoka embraced Buddhism after witnessing the massive bloodshed in the Kalinga War.

- This war had a profound impact on him, leading to his conversion and commitment to spreading peace.

- Option 2: Battle of Buxar

- This was fought in 1764 between the British East India Company and a coalition of Indian states.

- It had no connection to Emperor Ashoka or Buddhism.

- Option 3: Battle of Haldighati

- This battle took place in 1576 between the forces of Maharana Pratap and the Mughal Empire.

- It is unrelated to Ashoka.

- Option 4: Battle of Tarain

- These battles were fought in the 12th century between the Chahamana king Prithviraj Chauhan and Muhammad of Ghor.

- This event predates Ashoka by several centuries.