"Did you turn the fridge on?"
I sense the hints describe the phrasal verb "to turn" rather than "to turn [sth] on". It treats the on as a partical in its own right, not as part of the infinitive phrase.
On the learners' side, you are only shown three hints. On our side, there can be more of them. And we have "włączyłeś" in the system.
But there are four equally correct answers (or even nine if we consider the formal forms), so the system chose three of them and apparently didn't show "włączyłeś" (to one man). But "włączyłaś" (to one woman), "włączyłyście" (to a group of women) and "włączyliście" (to a group of men or a mixed group) are equally probable without further context.