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
A. Disjoint with total specialization
B. Disjoint with partial specialization
C. Overlap with total specialization
D. Overlap with partial specialization