I personally tend to say "I'm an American." But all of the choices you listed work.

Personally, I would say "I'm from the US" or "I'm from the United States". I would imagine it varies from person to person.

As someone from the US, I would say that it depends on the type of person who is being asked this question. For instance, as someone who has traveled a bit, I would never say that I am from America. I think this is a dated term (albeit there are many "Americans" that would disagree) as "America" encompasses many different countries technically speaking (North America - Mexico, US, Canada, even all the countries which we refer to as being a part of Central America, etc. & then of course there is South America - Columbia, Brazil, Ecuador, Bolivia, Argentina, etc). I would say I am from "the states", the "United States", or the "US" and I don't think there is a reason for my choosing any one of these specifically (apart from the reason I gave above which is what I do not choose). Lastly, it does too depend on what language I am speaking because for example in Spanish there is a noun to describe one's nationality that we don't have in english which is "estadounidense". In american english (and in much of the english speaking word) this doesn't exist. All we have is "American" which I'll only use if I have to. Otherwise, I'd say "I am a United States citizen". Best, Luke

I would say the 3rd and 4th are the most common, then the 1st one and probably the 2nd one would be last. That's just my opinion. It's probably going to change from person to person. If they are in South America, they might emphasize the US and not just say America.

What is the question?