It made many countries angry ______ the NATO, without the permission from the UN, started a war in Yugoslavia because of the problem of Kosovo.

1. A.
   when
2. B.
   because
3. C.
   that
4. D.
   if

It made many countries angry ______ the NATO, without the permission from the UN, started a war in Yugoslavia because of the problem of Kosovo.

A. when        B. because     C. that    D. if