Correct Answer: ATo preserve end users' profile and application customization settings while deploying Windows RDS desktops, using Horizon instant clone RDS hosts with User Environment Manager is the best option. User Environment Manager (UEM) allows for the management of profile settings and application configurations, ensuring that these customizations are retained across sessions. Additionally, the use of Horizon instant clone RDS hosts ensures quick and efficient deployment of the desktops. App Volumes, while crucial for application deployment, does not support writable volumes in an RDSH environment for user-specific data and settings.