18. Relational algebra A) Is declarative B) Is a schema definition language C) Is a query language D) Is a schema modification language 19. The advantage of using 3NF is that A) It enforces atomicity B) It enforces consistency C) It eliminates mvd redundancy D) It preserves functional dependencies 20. If all attributes of R are prime then A) R is in BCNF B) R cannot be losslessly decomposed C) R cannot be divided D) R is in 3NF 21. Given R(A, B,C, D, E) and A BC, B C,D E. Which of the following is a 3NF decomposition of R? A) AB, CD, DE, AB B) ABC, BC, DE C) BC, ABC, BDE D) ABC, AD, DE 22. Given (R,F), which statement is false? A) It is in 2NF but not in BCNF B) It is in 1NF but not in 3NF C) It is in BCNF and it is not in 3NF D) It is in 2NF but not in 3NF 23. If a minimal cover has 10 fds, any set of 12 fds cannot be a minimal cover A) True B) False 24. Which anomaly is NOT avoided by the "repeatable read" isolation level? A) Ww B) Phantonm C) Dirty Read D) none