A B C is a set of attributes. The functional dependency is as follows

AB  ->   B

      AC ->    C

         C ->    B

            a) is in 1NF

            b) is in 2NF

            c) is in 3NF

            d) is in BCNF

 (a) is in 1NF since (AC)⁺ = { A, B, C} hence AC is the primary key. Since C  -> B is a FD given, where neither C is a Key nor B is a prime attribute, this it is not in 3NF. Further B is not functionally dependent on key AC thus it is not in 2NF.  Thus the given FDs is in 1NF.