A. B, and C work in Beijing, Nanjing, and Chengdu. Their occupations are doctors, actors, and teachers. Known: A does not work in Beijing, B does not work in Nanjing; not teachers in Beijing; doctors in Nanjing; B is not an actor. So, where do A. B, and C work? ['Nanjing, Chengdu and Beijing.', 'Chengdu, Beijing and Nanjing.', 'Nanjing, Beijing and Chengdu.', 'Chengdu, Nanjing and Beijing.']