Ok lets analyze the question piece by piece...
Given a remote client R, that has valid reference to session beans A and B
As R (a remote client) has "valid" reference this means that it has a remote reference to A and remote reference to B.
1. R cannot pass his reference for A, to B
This is not a right choice because R can pass his remote reference of A to B as per the Spec "A client can pass a remote home object reference to another application".
and given that A is a local client to B
Although R has a remote reference to B, A has a local reference to B. (yes it is possible, but should be done with attention due to the reasons stated in page, 164 of HFEJB).
So choice 2 would be right because we cannot pass a local reference (A) to a remote reference (B to R).
Choice 3 is not right because, A can invoke methods on B.
Hope this helps...