The correct option is D the assassination of President Garfield.
The event that brought the issue of civil service reform to the fore during the Gilded Age was the assassination of President Garfield. On July 2, 1881, less than a year after President James Garfield was elected the 20th president of the United States, he was shot by Charles Guiteau. It took the wounded president more than two months to succumb to his wounds; he died on September 19th, 1881.