The correct answer is option 1, General Dyer. The Jallianwala Bagh tragedy was a significant event that took place on April 13, 1919, in Amritsar, India. General Reginald Dyer, who held the rank of Brigadier General at the time, was responsible for the incident.

Option 2, Arthur Wellesley, is not related to the Jallianwala Bagh tragedy. He was a British soldier and statesman who served as the Duke of Wellington and played a prominent role in defeating Napoleon Bonaparte at the Battle of Waterloo.

Option 3, General Harris, is also not connected to the Jallianwala Bagh tragedy. There have been several generals with the name Harris throughout history, but none of them were involved in this specific event.

Option 4, Colonel Wellesley, is not relevant either. The name Colonel Wellesley does not refer to a specific individual who played a part in the Jallianwala Bagh tragedy.

Therefore, the correct answer is option 1, General Dyer.