8) Which of the following statements is incorrect? (A) Both primary and clustering indexes are nondense. (B) A secondary index can be either dense or nondense. (C) The scheme of multilevel index can be used on any type of index, including primary, clustering, or secondary index. (D) None of the above. (2) Consider the relation schema R=(A,B,C,D) and the set of functional dependencies F:{ABCD,BCAD,DB}. Which of the following statements is incorrect? (A) The relation R satisfies 3NF. (B) The relation R violates BCNF. (C) Suppose that R is decomposed to R1(A,C,D) and R2(B,D). The decomposition has the lossless join property. (D) Suppose that R is decomposed to R1(A,C,D) and R2(B,D). The decomposition has the dependency preserving property. (3) Which of the followings is not the informal guideline that may be used as measures to determine the quality of relation schema design? (A) Designing the schema using either the top-down or bottom-up design methodology. (B) Making sure that the semantics of the attributes is clear in the schema. (C) Reducing the redundant information in tuples. (D) Disallowing the possibility of generating spurious tuples. 4) In what normal form is the relation schema R=(X,Y,Z, W) with respect the functional dependencies F={XYZ,XYW,ZX,WY} ? (A) the first normal form (1NF). (B) the second normal form (2NF). (C) the third normal form (3NF). (D) the Boyce-Codd normal form (BCNF)