You generate an Entity Data Model from your application database. The resulting model includes an entity named Person. The Person entity type has two properties - HireDate and EnrollmentDate. You add entity types Instructor and Student. You need to modify the model to ensure the following:
* All Person rows with a null EnrollmentDate and a nonnull HireDate must map to the Instructor type.
* All Person rows with a nonnull EnrollmentDate and a null HireDate must map to the Instructor type.
* Application code must be able to refer to both generated classes by using a common base class.
What should you do? (Each correct answer presents part of the solution. Choose two.)