Final answer:
Darcie is likely using a proprietary DBMS, as she has hired a programmer for custom changes which suggests that the DBMS is neither open-source (which would freely provide access to the source code) nor a simple relational model.
Step-by-step explanation:
If Darcie has hired a programmer to make custom changes to a Database Management System (DBMS) she plans to move her business database, she is likely using a proprietary DBMS. A proprietary DBMS is software that is owned by a company and requires a license to use. Modifications to such a system typically need the involvement of programmers who have specialized knowledge of the DBMS, which might be closed source. Other types of DBMS, such as open-source, allow anyone to access and modify the source code but typically do not require hiring a programmer for custom changes because users can do this themselves. A relational DBMS refers to the type of database model it employs (storing data in tables related to each other), which does not necessarily relate to the ability to customize the software. Similarly, DBaaS (Database as a Service) is a cloud-based service model and could be open-source or proprietary.