Consider the entity-relation (ER) diagram shown in the exhibit.

STUDENT(

Student_Number: integer NOT NULL

Name: variable length character string length 20 NOT NULL)

Primary Key Student_Number

CLASS(

Class_Num: integer NOT NULL

Class_Name: integer NOT NULL)

Primary Key Class_Num

STUDENT(

Student_Number: integer NOT NULL

Name: variable length character string length 20 NOT NULL)

Primary Key Student_Number

CLASS(

Class_Num: integer NOT NULL

Class_Name: integer NOT NULL)

Primary Key Class_Num

Foreign Key Class_Num References STUDENT

STUDENT(

Student_Number: integer NOT NULL

Name: variable length character string length 20 NOT NULL)

Primary Key Student_Number

STU_CLASS(

Student_Number: integer NOT NULL

Class_Num: integer NOT NULL)

Primary Key Student_Number

CLASS(

Class_Num: integer NOT NULL

Class_Name: integer NOT NULL)

Primary Key Class_Num

STUDENT(

Student_Number: integer NOT NULL

Name: variable length character string length 20 NOT NULL)

Primary Key Student_Number

STU_CLASS(

Student_Number: integer NOT NULL

Class_Num: integer NOT NULL)

Primary Key Student_Number, Class_Num

CLASS(

Class_Num: integer NOT NULL

Class_Name: integer NOT NULL)

Primary Key Class_Num