The Treaty of Amritsar was a key agreement that was concluded between Maharaja Ranjit Singh and Lord Minto. The treaty itself was signed on April 25, 1809, in the city of Amritsar.
Option 1, Lord Cornwallis, is incorrect as he was not involved in the signing of the Treaty of Amritsar. He served as Governor-General of India from 1786 to 1793 but played no role in this particular treaty.
Option 2, Lord Dalhousie, is also incorrect as he served as Governor-General of India from 1848 to 1856, which is many years after the Treaty of Amritsar was signed in 1809.
Option 3, Lord Hastings, is also incorrect as he served as Governor-General of India from 1813 to 1823, again after the Treaty of Amritsar was signed.
Therefore, the correct answer is option 4, Lord Minto. He was the Governor-General of India from 1807 to 1813 and played a significant role in the signing of the Treaty of Amritsar.