Consider the Gradebook ER diagram with cardinality ratios and structural constraints: Figure 2.15 Understanding Databases: Concepts and Practice, Dietrich, Wiley, 2021 Represent the given Entity Relationship diagram as a relational database schema using a textual schema summary. Use the attribute names as indicated on the ER diagram. Indicate the candidate key(s) of each relation. For each relation list foreign key(s) (if any) and the primary key each foreign key references. Also, the resulting design should avoid redundancy and the use of null values. The textual schema summary for relation courseoffering relation is provided as a sample. Use this description as a model for textual schema summary for other relations in the database schema..