Final answer:
The Link Generator is used to create external links on an HR Case form, whereas HR Services, Restricted Caller Access, and COE Configuration serve different purposes within the application.
Step-by-step explanation:
To create a link on an HR Case form that accesses information outside the application, the correct feature to use is Link Generator. The Link Generator allows users to create hyperlinks that can direct users to external websites or resources. In contrast, an HR Service is a record that defines a task or activity within the HR scope, Restricted Caller Access controls security access, and COE Configuration relates to setting up Centers of Excellence within the HR module. Therefore, when embedding external links in HR Case forms, the Link Generator is the tool designed for this purpose.