To set and later update the background color of all buttons in an application:
A: The application skin. The skin rule in Pega is designed to define and control the visual style of UI elements across an application. By modifying the button styles within the application skin, you can set the background color for all buttons and easily update it as needed without altering each button individually. This centralizes style management and ensures consistency across all portals.

Configuring a mobile channel in App Studio supports various features that enhance the user experience and application security on mobile devices:
C: Configure a left swipe behavior to open a message. This use case is supported by configuring gesture-based interactions in a mobile app, allowing users to use swipe gestures to access functionalities like opening messages, which enhances usability and interaction in the mobile environment.
D: Lock the application after 20 minutes of inactivity. Setting security features such as automatic locking after a period of inactivity is crucial for maintaining security on mobile devices, protecting sensitive data from unauthorized access.

To guide users through an application form effectively without requiring formal training, adding instructions directly to the assignment is the most direct and effective method. This approach allows specific guidance to be provided at the point of interaction, where users are making decisions or entering data. Instructions can include context-specific tips, examples of expected input, or clarifications on the task requirements. This ensures that users understand exactly what is needed at each step, facilitating smoother and more accurate completion of forms.