—Is that man Mr Hu?

—That ______ be Mr Hu. Because he has gone to Japan with his wife.

—Is that man Mr Hu?

—That ______ be Mr Hu. Because he has gone to Japan with his wife.

1. A.
   could
2. B.
   can’t
3. C.
   might
4. D.
   must

—Is that man Mr Hu?
—That ______ be Mr Hu. Because he has gone to Japan with his wife.