The correct option is B The British troops warned the people to leave the area before firing.
General Dyer with his troops fired at the unarmed crowd at the Jallianwala Bagh, a public garden in Amritsar, on 13 April 1919. He sealed off the garden's only exit and commanded his troops to open fire on the people without warning. The firing continued until the troops ran out of ammunition. General Dyer later declared that through this action, he wanted to sow fear in the mind of the Satyagrahis.