B. angered people in other Latin American countries.
The Dollar Diplomacy was Taft's foreign policy plan to remove military intervention in Latin America but remain in economic control.
Dollar Diplomacy promised the removal of American troops however to maintain economic control, the military was often used to intervene. In Nicaragua, the military was used to stage a political coup (overthrow) so bring in a pro-US government. This angered many in Nicaragua as well as surrounding countries. There was fear the US would continue imperial control, manipulating the newly formed governments in Latin America.
Several meanings could be agvined to this. On face value, Dr. King is saying that the men who lynched Emmett Till were morally bankrupt but hid behind Christianity and rationalized their actions for murdering Emmett for allegedly flirting with a married white woman.
