Consider the following 3NF relations about a sorority or fraternity:
a. Foreign keys are not indicated in these relations. Decide which attributes are foreign keys and justify your decisions.
b. Draw an E-R diagram for these relations, using your answer to part a.
c. Explain the assumptions you made about cardinalities in your answer to part b. Explain why it is said that the E-R data model is more expressive or more semantically rich than the relational data model.