There isn’t any difference between the two, I really don’t know ________．

A.where to choose

B.which to choose

C.to choose what

D.to choose which

答案及解析： B

解析：

前面已经提到是两个，所以要用到which，表示从这两个里面选择;which to choose属于“疑问词+动词不定式”结构，这种结构经常在句子里面作主语、宾语和表语。