The leader of the Santhal Rebellion, Sidhu Manjhi, played a significant role in the uprising. Here's the reason for his leadership:

Oppression and Discontent: The Santhal Rebellion of 1855-1856 was a response to the oppressive policies and land settlements imposed by the British colonial administration, which had adverse effects on the Santhal tribal community. 

Leadership Role: Sidhu Manjhi, along with his brothers Kanhu and Chand, emerged as prominent leaders during this period. 

Rebellion and Resistance: Sidhu Manjhi and his brothers mobilized the Santhals to resist the oppressive policies, and they were at the forefront of the rebellion. 

Legacy: The Santhal Rebellion, led by Sidhu Manjhi and his brothers, remains a significant event in Indian history and a symbol of tribal resistance against British colonialism.

So, the correct option is [2].