In each group, name any answer which matches the first category to reveal the second category, then name any answer which applies to both categories to reveal a third, and so on.
Great quiz! Correct me if I’m wrong but I believe Washington DC should work for the blue categories, as “DC” is not part of the name of the city, but just indicating the federal district.
Actually, on all quizzes we use "Washington, D.C." and even Wikipedia does as well, stating "also known as Washington", indicating it treats them as different things. Yes it refers to the district, but it's also a part of the name.
Just like Kansas City indicates that it's Kansas, the city, instead of Kansas, the state. But it's still part of the name.
It's funny that Buenos Aires also contains the letter I, so i half-expected the last clue to be that too, just to make it more difficult. Are there any other capitals that contain all five vowels?
Just to let you know that Washington works for the Blue categories up to "which are only one word" where it does not work anymore although Washington is only one word.
Just like Kansas City indicates that it's Kansas, the city, instead of Kansas, the state. But it's still part of the name.