Mangal Pandey was hanged to death for attacking British officers in Barrackpore on ______.

29 March 1857

The correct answer is Option 4- 29 March 1857

March 29, 1857: Mangal Pandey attacked British officers, sparking the first major incident of what later became known as the Indian Rebellion of 1857.
Fearing a wider uprising: British authorities expedited his execution, moving the initial date from April 18th.
April 8, 1857: Mangal Pandey was hanged in front of all Indian and British units stationed in Barrackpore

(As per the given options, the most appropriate answer is Option 4- 29 March 1857 which corresponds with the date when Mangal Pandey attacked the British officers).