Susan B Anthony, the American champion of woman's suffrage, was also a participant in the movement to end slavery.

【正确答案】 A

【答案解析】句中participant的意思是“参与者”，与它意思相近的词是partaker。其他选项ob—server“观察者”；leader“领导者”；supporter“支持者”都无此意。故选A。