What is the function of Azure Functions in data applications?

Azure Functions serves as a serverless compute service that executes code in response to triggers or events. This functionality allows developers to build applications that can respond dynamically to various inputs such as HTTP requests, messages from a queue, or timers, enabling event-driven architectures. Given this capability, Azure Functions can effectively handle tasks like data processing, automated workflows, or integrating services seamlessly.

In contrast, the other options describe functions that do not align with the purpose of Azure Functions. Creating graphical user interfaces pertains more to front-end development, storing relational data is primarily the role of database services like Azure SQL Database, and managing cloud service security involves broader cloud management and governance strategies. Hence, the choice that highlights the execution of code in response to events aligns perfectly with the core functionality of Azure Functions within data applications.