i have no idea which was better so I took ___ of them 代词

问题描述:

i have no idea which was better so I took ___ of them 代词
i have no idea which was better so I took ___ of them   为什么答案是 both   为什么 all和 none  不行

both ---------二者肯定
all---------------三者以上肯定
none---------------三者以上否定