A client wants their application to have a very specific color scheme. Who's work is most likely to be affected?

The best choice for this scenario is the UI Designer, as they are directly responsible for creating and implementing the visual aspects of the application, including the color scheme. The UI Designer focuses on ensuring that the application's look and feel align with the client's branding and specifications. This role involves selecting appropriate colors, fonts, and layouts to create an aesthetically pleasing user interface that improves the user experience.

In contrast, a Frontend Developer may implement the design created by the UI Designer in code but is typically not the one who decides on the color scheme itself. The Database Administrator manages the data and database structure, which does not involve design elements like color schemes. Similarly, the Backend Developer focuses on the server-side logic and functionality of the application, which does not directly pertain to the visual presentation or user interface. Consequently, the UI Designer's work is the most affected when a client specifies a particular color scheme.