What option must be selected to prevent a user from logging into the ServiceNow User Interface?

Choosing "Web service Access only" is the correct option to prevent a user from logging into the ServiceNow User Interface (UI). This selection limits the user’s access strictly to web services, which means they will not have the ability to access the ServiceNow platform through the standard UI. Instead, their permissions will be confined to interacting with the system through APIs or web services, effectively blocking any direct access to the UI.

On the other hand, designations like "Internal Integration User," "Admin Access Only," and "Guest Access" do not serve the same function. An "Internal Integration User" might imply permissions that allow for certain UI interactions within internal operations. "Admin Access Only" would grant administrative privileges that inherently include UI access. "Guest Access" typically provides minimal permissions to access certain public or shared resources in the application's front end, which also contradicts the intent of fully preventing UI login. Thus, the selection of "Web service Access only" is precise for restricting UI access, ensuring the user remains limited to back-end functionality without interacting with the interface directly.