Final answer:
An embedded database system is the best choice for simple applications not expected to change and used only by one person, due to its integration with the application and single-user optimization.
Step-by-step explanation:
If the database and applications are simple, not expected to change, and are only used by one person, the best choice would be an embedded database system. An embedded database system is integrated into an application, providing a tightly coupled database solution that can efficiently manage data for standalone applications. It's typically lightweight, doesn't require network connectivity to operate, and is ideal for single-user scenarios.