made easy test series - lossless join and dependency preserving

Question

How is A answer?

Comments

I think answer should be c

Answer 1

Lossless: B is the intersection between two tables and B is the key in table 2.

Dependency preserving :
FD on R1 : A -> B

FD on R2 : B->D and D -> BC

union of these two can cover original FD set.

Hence dependency preserving.

Comments

I think there is a mistake in the question as in the first FD A->D, there should be A->B.

Isn’t it?

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A->B fd is not in question. how did you do that? Can anyone please explain where the given decomposition is dependency preserving or not.