That's still a bad question: the behavior is implementation-defined according to the standard, so having "implementation-defined" as a wrong option is ambiguous

That's still a bad question: the behavior is implementation-defined according to the standard, so having "implementation-defined" as a wrong option is ambiguous and confusing. The question would be fine (given that note) if "impementation-defined" was not an option, like for example the question about "SCHAR_MAX == CHAR_MAX".