C died of poisoning. To this end, A and B were tried by the judge. A: If it was murder, it must be B. B: If this was not suicide, it was murder. The judge made the following assumption: 1) If neither A nor B lied, this is an accident. (2) If one of A and B lied, then this is not an accident. The final facts show that the judge's assumption is correct. Then C? ['It was an accident.', 'It was suicide.', 'was murdered.', 'May be murdered or suicide.']