question: united kingdom:london
choices.label: A B C D
choices.text: united states:california china:beijing tokyo:japan portugal:spain
explanation: "london" is the capital of the "united kingdom". "california" is not the capital of the "united states", washington is the capital of the "united states". "beijing" is the capital of "china". "tokyo" is actually the capital of "japan", but it is not explicitly written into the law. "portugal" and "spain" are both countries.
relation: united kingdom london R2.3