Answer:
B. The passing of the Civil Rights Act of 1964
Step-by-step explanation:
The passing of the Civil Rights Act of 1964 played a significant role in changing the direction of the Republican Party. This landmark legislation aimed to end racial segregation and discrimination. As a result, it prompted a shift within the Republican Party toward supporting states' rights, as some members of the party opposed the federal government's intervention in state affairs, particularly on issues related to civil rights. This marked a departure from the party's original antislavery ideology in the 1860s and led to a realignment of political positions.