Explanation:

- Option 1: Piyali Barua

- Piyali Barua was an associate of Maniram Dewan.

- He played a significant role in the revolt but wasn't the central figure.

- Option 2: Purandar Sing

- He was the last king of Assam's Ahom kingdom.

- He tried to regain his kingdom but was not the central figure of 1857.

- Option 3: Bahadur Gaoburah

- This name is less prominent in the context of the 1857 revolt.

- Not recognized as a central figure in Assam's revolt.

- Option 4: Maniram Dewan

- Maniram Dewan was a key leader in the 1857 revolt in Assam.

- He organized efforts against British rule.