About Question enthuware.ocpjp.v8.2.1235 :

[badbishop]

I have picked the last option fingers crossed, because the rest made no sense at all. But, strictly speaking, Future<V> is not exactly a "result" in the common meaning of the term - i.e., something that is useful in it's own right, and an attempt to call Future<V>.get() may block, if the result is yet to be achieved.

[admin]

The problem statement doesn't imply that Future is the result. It asks which of the types from java.util.concurrent package will be required to get the result without blocking. You will need Future. That it is not sufficient is a different issue.