Assume that AB → C, C → D and D → A are simultaneously satisfied by a relation r(R). What are the candidate keys of this relation?

Assume that AB → C, C → D and D → A are simultaneously satisfi

1.	Assume that AB → C, C → D and D → A are simultaneously satisfied by a relation r(R). What are the candidate keys of this relation?
A.	AB, CD and AD
B.	AB and CD
C.	AB and DB
D.	ABCD and BC
Answer» D. ABCD and BC

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Assume that AB → C, C → D and D → A are simultaneously satisfied by a relation r(R). What are the candidate keys of this relation?

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