Which factor played the largest role in the african national congress's
transition from insisting on peaceful protest to considering violence?

a. south african police opened fire on a group of citizens, killing
dozens of them.

b. rebel forces from algeria took control of the south african
independence movement.

c. south african leaders were not tried for human rights abuses after
apartheid ended.

d. u. s. president ronald reagan refused to punish south africa for
its apartheid policies.