President Truman on March 21, 1947 issued an executive order, initiating a comprehensive investigation of the loyalty of all federal employees. This was the beginning of ______.
A、McCarthyism
B、Clearing out Soviet spies
C、widespread persecution of Communists and progressive people
D、persecution of federal employees
【正确答案】：C
【题目解析】：1947年3月21日，杜鲁门总统发布了一项行政命令，对所有联邦雇员的忠诚度进行全面调查。这是对共产党人和进步人士的大范围迫害的开始。
