Original sentence: UNESCO marks March 21 as the yearly International Day for the Elimination of Racial Discrimination, in memory of the events that occurred on March 21, 1960 in Sharpeville, South Africa, where police killed demonstrators protesting against the apartheid regime
Edited sentence: UNESCO marks March 21 as the yearly International Day for the Elimination of Racial Discrimination, in memory of the events that occurred on March 21, 1960 in Sharpeville, South Africa, where police killed student demonstrators peacefully protesting against the apartheid regime