Consider the relation Student(stuid, dept, clsroll) with FDs: FD1: stuid → dept, FD2: dept → stuid, FD3: stuid → clsroll, FD4: clsroll → stuid, FD5: dept → clsroll. Which FDs can be removed to obtain a canonical cover? A. FD2 and FD3 B. FD1 and FD5 C. FD5 D. FD1
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Correct answer: B. A, C only
Explanation
Removing FD5 works, since dept → stuid → clsroll. Removing FD2 and FD3 also works: stuid → dept → clsroll → stuid still connects everything. Removing FD1 (with or without FD5) loses stuid → dept. So A and C.
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