The correct answer is: A. Munger – Bhagalpur.
The Santhal Rebellion, also known as the Hul, was an uprising of the Santhal people against the British East India Company in 1855. The rebellion began in the Santhal Parganas, a region in the present-day Indian states of Jharkhand and Bihar. The Santhals were a tribal people who had been displaced from their traditional lands by the British. They were also subjected to heavy taxation and forced labor. The rebellion was led by Sidhu and Kanhu Murmu, two Santhal brothers. The rebels captured several towns and killed many British officials. The rebellion was eventually suppressed by the British, but it had a significant impact on the British Raj. It led to the creation of the Santhal Parganas district and to the introduction of reforms to improve the lives of the Santhal people.
The other options are incorrect because they do not correspond to the region where the Santhals declared their government in 1855. Option B, Bhagalpur – Rajmahal, is incorrect because the Santhal Parganas are located to the south of Bhagalpur. Option C, Gaya – Munger, is incorrect because the Santhal Parganas are located to the west of Gaya. Option D, Shahabad – Gaya, is incorrect because the Santhal Parganas are located to the south of Shahabad.