posted 22 years ago
I believe the correct answer for this question is (b) Supplier.
Supplier is not an abstract class, not in this diagram so the object in the sequence diagram may be both, Supplier OR PreferredSupplier.
From the diagram we can't conclude that each Supplier has to be a PreferredSupplier, only the opposite way, so putting in Supplier is correct for every concrete Supplier-Object.
And, about multiplicity of generalizations, I'm pretty sure that you can't do something like that in UML.
Multiplicity belongs to assoziations, it tells something like Class A has/knows one or many B's. How could you read this for a generalization? Class A is many B's? Makes not much sense to me.
Chris