it relied on the sum of the angles of a triangle adding up to 180 degrees, which is true on the usual flat surface (euclidean geometry) but not necessarily true otherwise. you can even have a triangle with 3 right angles on a sphere, for instance.
so some kid wrote in "none of the above" or the seemingly incorrect "b" response instead of the intended correct response "c" or whatever it was.
eventually, i believe, the kid and anyone else who responded similarly got credit for the correct answer, as did everyone who gave the intended answer.
for what it's worth, i've rarely taken a complete test that didn't have some problem along these lines with at least one question. it's actually hard to develop a comprehensive test and not make a mistake somewhere. a question assume that zero divided by "x" is always zero, forgetting that zero divided by zero is undefined, for example.
that said, they should obviously put these tests through a very thorough quality assurance process if they're going to be so standardized.