Ans: B.Lord Dalhousie

Exp: The British Governor General and Viceroy who served for the longest period in India was Lord Dalhousie.

Governor-General of India
In office 12 January 1848 – 28 February 1856
Monarch	Victoria
Prime Minister	Lord John Russell The Earl of Derby The Earl of Aberdeen The Viscount Palmerston
Preceded by	The Viscount Hardinge
Succeeded by	The Viscount Canning