The correct answer is A. Caused American public to change their attitude toward war, fueling a broader anti-war movement.
Step-by-step explanation
My Lai is the name for a massacre carried out on March 16, 1968 by the United States Army led by Calley against Vietnamese civilians during the Vietnam War. Although it was not immediately known in the United States, after more than a year there was evidence of this terrorist act that prompted the American peace movement to demand an end to the United States' participation in this confrontation. According to the above, the correct answer is A. Caused American public to change their attitude toward war, fueling a broader anti-war movement.