It all seemed to be repeat but she never actually made the Potion before so the chances of a correct answer was very very unusuall... So the substance of the allergy was what she had to go with! Or maybe something else..

LuLu looked at the other students that thought outside the box... Water? W-well.. Yes! But...

She shook it off quickly and turned to the proffeser and raised her hand ''Well of course there is the object/thing, that the particular person is allergic to, but if thats the case then you need an anti allergy ingredient,'' she didn't know what.. what it was, but it was an answer!