12. If a relation has two sets of independent attributes then A) independent redundancy will appear B) multivalued dependency redundancy will apperr C) BCNF redundancy will appear D) deletion anomaly will appear 13. The following normal form preserves functional dependencies A) BCNF B) 4NF C) 3NF D) 2NF 14. The following normal form eliminates all redundancies (including multivalued) A) BCNF B) 4NF C) 2NF D) None of the above 15. Normalization should take place A) before designing an E/R diagram B) after creating the tables in the DBMS C) before entering the schema in the DBMS D) after the first query 16. If (A, B) is the only key of R(A, B,C, D) then A)AB C is a BCNF violation B) C B is a 3NF violation C) (A, B, C) is a superkey D) A C 17. If X Y and Y Z then the following non-trivial fd can be obtained