The correct option is D.
Explanation
The Revolt of 1857, also known as the First War of Independence, was a major uprising against the British East India Company. While localized incidents occurred earlier, the organized military rebellion began in the cantonment of Meerut.
- 29 March 1857: This date marks the individual act of defiance by Mangal Pandey of the 34th Native Infantry at Barrackpore. While significant, it was an isolated incident and not the start of the general uprising.
- 8 April 1857: This was the date of the execution of Mangal Pandey following his court-martial for the events at Barrackpore.
- 10 May 1857: On this day, the sepoys of the 11th and 20th Native Infantry stationed at Meerut broke into open rebellion. They released their comrades who had been imprisoned for refusing to use the greased cartridges, killed British officers, and set fire to the cantonment. This event is historically recognized as the formal commencement of the 1857 Revolt.
- 11 May 1857: On this morning, the rebellious sepoys from Meerut reached Delhi, crossed the Yamuna, and appealed to the Mughal Emperor Bahadur Shah Zafar to lead the movement.
Key Takeaway: The formal outbreak of the 1857 Revolt occurred on 10 May 1857 at Meerut, transitioning the unrest from individual acts of defiance to a collective military mutiny.