The correct option is A Dyer
Jallianwala Bagh Massacre was the incident in which British troops fired on a large crowd of unarmed Indians in Amritsar killing several hundred people and wounding many hundreds more. On 13 April 1919, thousands of people were gathered at Jallianwala Bagh in Amritsar. General Dyer arrived there with armed troops and ordered ruthless firing on the uninformed crowd.