What functionality does SAIL provide to designers?

The functionality that SAIL (Simultaneous Application Interface Layer) provides to designers is centered around enabling the development of applications that can be deployed across multiple platforms from a single source. This capability is pivotal because it allows developers to create user interfaces that are responsive and adapt well to different devices, whether they are accessed via web browsers on desktops, tablets, or mobile phones.

SAIL achieves this through its focus on a robust and flexible design system that encapsulates best practices in user experience and design, which ensures that applications maintain consistency and functionality regardless of the platform they are being used on. This cross-platform deployment simplifies the development process, reduces the need for platform-specific adjustments, and enhances the user experience by providing a seamless interface.

The other options do not fully capture the essence of what SAIL provides. For instance, merely allowing the visual design of apps does not encompass the full functionality of SAIL, as it goes beyond aesthetics to include functional deployment capabilities. Writing extensive programming code contradicts SAIL's design philosophy, which emphasizes low-code solutions and ease of use. Lastly, configuring network settings is outside the scope of SAIL's purpose, which focuses on application interface and user interaction rather than infrastructure management.