Select the correct interpretations of the following EERD from the list given below: $(3$ points$)$

There may be a STUDENT who is neither a GRADUATE nor an UNDERGRAD.

The subtype discriminator for Graduate and Undergrad is STU$\_$TYPE.

Each EMPLOYEE occupies an OFFICE, and each OFFICE is occupied by one EMPLOYEE.

There may be an EMPLOYEE who is neither an ADMINISTRATOR nor a PROFESSOR.

A PERSON can be an EMPLOYEE or a STUDENT, but not both.