The country names used are the same as in the Countries Of The World quiz. The generally accepted name for the USA is "United States", which contains only one I.
^ the generally accepted name for the USA on these quizzes is "USA"; therefore, in a situation such as this, it should be accepted, just as "Bosnia" and "Vatican" are accepted, even though only their formal names contain the required extra "i".
USA is an accepted type-in, however the listed name in the Countries quiz is "United States". Likewise, the quiz lists Bosnia's and Vatican's full names, though the shortened versions are accepted as type-ins.