Use of a supertype/subtype relationship is necessary when which of the following exists?

[A].	An instance of a subtype participates in a relationship that is unique to that subtype.
[B].	An instance of a subtype participates in a relationship that is the same as the other subtypes.
[C].	Attributes apply to all of the instances of an entity type.
[D].	No attributes apply to any of the instances of an entity type.

Answer: Option A

Explanation:

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