惟有相互了解，国与国才能增进信任，加强合作。

A、Without mutual understanding, it is impossible for countries to build trust and promote cooperation with one another.
B、It is mutual understanding which makes it possible for countries to build trust and promote cooperation with one another.
C、Only mutual understanding can be one way for countries to build trust and promote cooperation with one another.
D、Mutual understanding is one way only for countries to build trust and promote cooperation with one another.