7 2 points ER modeling has been enhanced to include various real world cases. For example, in Dream Home company ER model, there is a Staff entity as a superclass, which has three subclasses by job roles in a position attribute - Manager, Marketer, and Contract Specialist - where contract specialists screen any potential problems of real estate contracts for sales and rent, and they also help prevent any lawsuits. Choose three most appropriate explanations about this ER modeling. (2 point) OOO (Figure) If the DreamHome company is a small-sized company working in only Milwaukee and will not expand its business to other areas, all the staff member data can be managed by one Staff entity regardless of their job position. All staff members should be included in one of the subclasses. The subclasses can share another subclass (i.e., a subclass of subclasses) based on common characteristics. If a DB designer design Staffentity first and then separate staff members by position, this process is called specialization. Each subclass has its own primary key. 8 2 points At the same time, in the enhanced ER modeling of the Dream Home company, the Staff entity has another set of subclasses based on employment contract - Full time and Part time as shown below. (The employee contract is irrelevant to real estate contract.) Choose two most appropriate explanations about this enhanced ER modeling. (2 points) (Figure) The subclasses are dependent to each other so that one subclass cannot have another relationship aside from the existing relationships. The subclasses are independent to each other so that one subclass can have another relationship aside from the existing relationships. Generalization process is done by organizing the Staff entity first and then making the subclasses. A staff member cannot be a manager of contract specialist Staff members should have either full-time contract or part-time contract regardless of their job positions. OOO 1 point Below is an example of a Staff relation. Which description is most inappropriate? Choose one. (1 point) (Figure) Each cell must have a one atomic (single) value. Tuple means a row or a record of a relation such as (SL21, John, White, Manager, M, 1-Oct-45, 30000, B005) Attribute means a named column of a relation such as StaffNo, position, and salary. Domain means a set of allowable values (or data type) such as NUMBER for the salary attribute. When adding a new attribute to the Staff relation, the DB designer can name it as "position". a