Q# Answer the following parts using database knowledge:
(a) If a functional dependency X→Y holds in two relations R and S, does the functional dependency X→Y still hold on the relation R NJ S (where NJ stands for “natural join”)? Justify your answers.
(b) Will you agree that all the relationships involving a weak entity set should connect to that weak entity set using double line? If you do/don’t agree, please explain briefly in either case.
(c) What is the consequence of inserting rows into a “view” V when: (i) V is defined based on one physical table (ii) V is defined based on multiple tables
(d) Compare and contrast the three types of single-level indices, i.e., primary index, clustering index, and secondary index, in terms of their （i） applicable conditions （ii） the kinds of supportable search/queries.