Both A and B may be invited to participate in an expert forum. Now A has learned the following information: (1) the forum organizer has decided to invite at least one of A or B. (2) the forum organizer has decided not to invite A (3) Forum organizer will definitely invite A. (4) Forum organizer decides to invite B. If two of the above messages are true and two are false, then:. ['Forum organizer decides to invite A. not B.', 'Forum organizer decides to invite B, not invite A.', 'Forum organizer decides to invite both A and B.', 'The forum organizer decides to invite neither A nor B.']