如果先行词是the only person,定语从句引导词是who还是that

问题描述:

如果先行词是the only person,定语从句引导词是who还是that
RT,有把握对的回答
网上说先行词有the only修饰用that,先行词有people,persons修饰用who
到底用那个,说明原因,

that,因为有the only