Chimpanzees in western Africa's Tai forest crack nuts by placing them on tree roots and striking them with stones,a lear

Chimpanzees in western Africa's Tai forest crack nuts by placing them on tree roots and striking them with stones,a learned behavior [probablyl unique to chimpanzees in that area].
A.probably unique to
B.probably unique about
C.probably it is unique to
D.that is probably unique with
E.having probably been unique to
请问这个Unique有什么固定搭配吗?我用排除法已经排除了CDE,就是在AB两者之间纠结...