My most famous relative of all, _______ who really left his mark on America, was Reb Sussel, my great-grandfather．
A.oneB.the oneC.heD.someone在线课程B
解析：
the one作同位语，指代上文中的“my most famous relative of all”。one作代词表示泛指，泛指某人或某物。he作主语，不作同位语。someone意为“某人”，表示泛指。