It is difficult to tell the twins ( ) because they look exactl

It is difficult to tell the twins ( ) because they look exactly the same.
A、apart
B、alike
C、aside
D、across
【正确答案】：A
【题目解析】：考核固定搭配 tell…apart… 把…区分。句子含义是很难辨别双胞胎，因为他们太像了。