单项选择题

已知字典dict1={"中国":"北京","法国":"巴黎","美国":"华盛顿"},执行语句dict1["中国"]="大北京"后,字典dict1的内容为?()

A."中国":"北京","法国":"巴黎","美国":"华盛顿"}
B."中国":大北京,"法国":"巴黎","美国":"华盛顿"}
C."中国":"大北京","法国":"巴黎","美国":"华盛顿"}
D."中国":"北京","法国":"巴黎","美国":"华盛顿","中国":"大北京"}