For a library, the entity type HOLDING has four subtypes: BOOK,AUDIO BOOK, DVD, and
Draw a separate EER diagram segment for each of the followingsituations:
a. At a given time, a holding must be at least one of thesesubtypes.
b. At a given time, a holding must be exactly one of thesesubtypes.
c. A holding may or may not be one of these subtypes. On the otherhand, a holding may be
any two (or even four) of these subtypes at the same time.