Change the Appointments table so when a APPOINTMENT$\_$ID is added a PET$\_$ID must be added. Select the correct SQL$.$

a$.$ MODIFY TABLE Appointments

MODIFY $($PET$\_$ID INTEGER NOT NULL$)$;

b$.$ CHANGE TABLE Appointments

MODIFY $($PET$\_$ID INTEGER NOT NULL$)$;

c$.$ ALTER TABLE Appointments

MODIFY $($PET$\_$ID INTEGER NOT NULL$)$;