The only Viceroy to be assassinated in India was

The only Viceroy of India to be assassinated was Lord Mayo. He served as the Viceroy from 1869 to 1872 and was known for his administrative reforms and efforts to strengthen the British administration in India.

Lord Mayo was assassinated on February 8, 1872, while visiting Andaman Islands. He was killed by Sher Ali, a convict who was reportedly angry over his harsh treatment and imprisonment. The assassination occurred at Port Blair, where Lord Mayo was inspecting the prison facilities.

His death marked a significant event in the history of British rule in India and highlighted the growing discontent and challenges faced by British officials in managing colonial governance.

Other options are not correct as they were not assassinated during their tenure:

Option A: Lord Harding served as Viceroy from 1844 to 1848 and was not assassinated.

Option B: Lord Northbrook served as Viceroy from 1872 to 1876 and died of natural causes.

Option C: Lord Ellenborough served as Viceroy from 1842 to 1844 and also died of natural causes.

Therefore, the correct answer is:

Option D: Lord Mayo