What are the referential constraints for the relations defined in these relation definitions?

Consider the following relation definitions:
STUDENT(
Student_Number: integer NOT NULL
Name: variable length character string length 20 )
Primary Key Student_Number
HOUSING(
Housing_ID: integer NOT NULL
Student_Number: integer NOT NULL
Building: variable length character string length 25 ) Primary Key Housing_ID
Foreign Key Student_Number References STUDENT(Student_Number) ON DELETE NO ACTION
ON UPDATE CASCADE
What are the referential constraints for the relations defined in these relation definitions?

A.
There is no relationship between changes inSTUDENT(Student_Number) and HOUSING(Student_Number).

B.
WhenSTUDENT(Student_Number) is changed or deleted, this modification or deletion will automatically be reflected in HOUSING(Student_Number).

C.
Modifications toHOUSING(Student_Number) are automatically reflected in changes to STUDENT(Student_Number), but deletions are not permitted.

D.
Modifications toSTUDENT(Student_Number) are automatically reflected in changes to HOUSING(Student_Number). For a deletion to occur from STUDENT(Student_Number), it must first occur in HOUSING(Student_Number).