The correct option is D Punjab was placed under martial law before the massacre.
On 10th April 1919, the British government had two prominent Congress leaders, arrested and deported to Dharamsala. This led to chaos across many cities, including Amritsar. To control the rising violence, the administration of the city was handed over to General Dyer. On 13th April, Baisakhi Day, a large crowd of at least 10,000 people gathered at Jallianwala Bagh. Since a large gathering was banned under the martial law imposed on the region, General Dyer asked his personnel to open fire in the field.