This one made me think. Even allowing for the general rule, 'when in doubt, sacrifice your Queen' I didn't find this one easy to spot at all. I don't even have the excuse of there being plenty of checking options because there are hardly any.
The position of the black queen should give a clue because it's about to check the white king. So you know the key-move has to be check & as lufbr points out, there are few of those to think about. Neither knight check does very much, so it has to be the queen. A little thought needed though, so 2 stars seems about right.