In the fight against child trafficking, the police rescued a boy. In order to determine his hometown, the police conducted an investigation: Informed person A said that he may be a Sichuanese or Guizhouese; informed person B said that he can't be Sichuanese; insider C said that he must be Sichuanese; insider D said that he was not from Guizhou. The police determined that the words of only one person could not be trusted. Based on the above information, the police can determine the boy's hometown ?:. ['Sichuan.', 'Guizhou.', 'It could be Sichuan or Guizhou.', "'t judge."]