Correct answer: D. Hunter Commission
Explanation: The direct answer is D: the Hunter Commission was appointed to inquire into the Jallianwala Bagh incident. On 13 April 1919, troops under General Reginald Dyer fired on a large crowd at Jallianwala Bagh in Amritsar. The British government later appointed the Disorders Inquiry Committee, commonly called the Hunter Commission, to investigate the disturbances and the action at Amritsar. A is wrong because the Simon Commission was linked to constitutional reforms and arrived later. B is wrong because the Indigo Commission concerned indigo cultivators and plantation grievances. C is wrong because the Lee Commission dealt with public services, not this massacre. D is correct. Exam cue: Jallianwala Bagh, 1919, Hunter Commission.