Boroughs and towns are not interchangeable in PA. In fact, the state does not use the classification 'town' at all; the sole exception is Bloomsburg. So, all places beginning with I are boroughs or cities, not towns.
Fun quiz but "Cities and Boroughs" would've been better than saying "Cities and Towns" when the only "town" is Bloomsburg and that's not on this quiz. As others have mentioned there are boroughs like Indiana for the letter I.