"What year is this year?"
It is actually useful as reign years are still widely in use.
wanikani puts it as nannen 「なんねん」. this answer on this needs to have a card for 「なんねん」何年
Remember: downvoting is for incorrect information being claimed as correct or for disallowed content, not for if someone doesn't understand. This person is asking a legitimate question and should not be downvoted.
It's frustrating that it's counted as 'incorrect' because they suddenly want a "?" attached to the 'ka' which is supposed to represent a question mark in a sentence. I think there's a flaw in this question's grader.