On an international train, passengers A, B, C and D from Britain, Italy, Japan and Germany happened to meet in a carriage. In addition to speaking their own language, each of them can speak one of the other three languages, one of which all three can speak. The conversations of the four passengers are as follows: (1) B does not speak English, but when A and C talk, he can translate for them; (2) A is Japanese, D does not speak Japanese, but they can talk without difficulty; (3) B, C, D can not find a common language to talk; (4) none of the four can talk in both Japanese and Italian.
the language that all three people can speak?
German