What provides guidance on what military information you can and cannot share with others?

Operational Security (OPSEC) is the correct choice because it encompasses the processes and practices designed to protect sensitive information from being accessed by adversaries. OPSEC identifies critical information that, if disclosed, could benefit an enemy or compromise military operations. This discipline focuses on preventing potentially damaging information from being inadvertently shared or leaked.

Sharing information about military operations, strategies, capabilities, or personnel can have significant security implications. Thus, OPSEC serves as a guide for determining what types of information are sensitive and need to be protected. It emphasizes the importance of maintaining the confidentiality of certain details that could compromise mission success.

Other options, while related to information security, do not specifically address the comprehensive framework for evaluating and protecting operational information in the military context as thoroughly as OPSEC does.