Which types should replace ?1,?2, ?3 in the following Scala function definition? def (xs:71, 73 = { [X,Y] g cas e Nil cas e y::ys f: ?2) : xs match f Nil f(y) => => :: g(ys, f) 71 ?2 ?3 = = = List [X] X= >ListY] List [T] 71 ?2 ?3 List [X] List(X=>Y] List [T] = = = 71 ?2 ?3 = List [X] = List [T] = List [T]