Final answer:
A security guard must discuss confidential information about security operations only with those who are authorized to receive it, reflecting the importance of operation security, legal and ethical considerations, and the practice of maintaining confidentiality in various professions such as law enforcement and journalism.
Step-by-step explanation:
The question relates to the appropriate handling of confidential information by security personnel. Given the contexts provided, the most appropriate and professional course of action for a security guard who comes into possession of confidential information about security operations is to discuss that information only with individuals who have been explicitly authorized to receive it.
This aligns with the need for businesses and organizations to maintain operation security, the protection of personal, financial, and medical information, and broader concerns about national security. It also reflects the legal and ethical considerations emphasized in the practice of granting anonymity, as well as the importance of confidentiality in law enforcement and journalism, exemplified by reporter's privilege and cases involving confidential government sources.
Therefore, the correct answer is D) anyone with whom the guard has been authorized to discuss the information.