"Which fruit do you like?"
Translation:Unapenda tunda gani?
Wapi means 'where'. Wepi means 'which', but is used only for wa-class nouns (Watu wepi?). Since tunda is 'ji-' class, an another correct translation would be Unapenda tunda lipi?. But, apparently the -pi construction is used less and less and gani is more common nowadays.