3. For a library, the entity type HOLDING has 4 subtypes: BOOK, AUDIO BOOK, DVD, and SOFTWARE. Draw a separate EER diagram segment for each of the following situations (put each diagram under the letter/instructions you are diagraming for): a) At a given time, a holding must be exactly one of these subtypes b) A holding may or may not be one of these subtypes. However, a holding that is one of these subtypes cannot at the same time be one of the other subtypes. c) A holding may or may not be one of these subtypes. On the other hand, a holding may be any two (or even four) of these subtypes at the same time. d) At a given time, a holding must be at least one of these subtypes