Final answer:
Jessica can best inform only U.K team members about an event by creating an Audience record for the U.K employees and adding it to the event. This method is effective and efficient for targeting information dissemination to a specific group.
Step-by-step explanation:
If Jessica wishes to make only the U.K team members aware of the details of an upcoming volunteer opportunity in December, the most efficient option from the provided choices would be to Create an Audience record for the U.K employees and add it to the event. Audiences can be defined based on various criteria, such as location, which would allow Jessica to easily target only those employees residing in the U.K. This process can be managed within a company's intranet or event management system where such functionalities are available. By creating an audience, Jessica ensures that information about the volunteer opportunity is disseminated effectively and exclusively to the intended group without having to add users individually or manage user-specific criteria records.
Other methods mentioned, such as creating User Criteria records or Access Control records, are generally more complex and may control access to the content rather than just its visibility to a certain group. Adding each U.K user individually to the event would be time-consuming and not practical for larger organizations.