What Event Served as a Catalyst for the Creation of the Pendleton

What event served as a catalyst for the creation of the Pendleton Act?

A) the growth of the Republican Party in the 1880s
B) the expansion of the federal bureaucracy in the 1880s —Consider This: Although patronage expanded the federal bureaucracy during the Gilded Age, it took a dramatic and unanticipated development to encourage civil service reform.
C) the assassination of James Garfield in 1881
D) the election of Rutherford B. Hayes in 1876