What is not authorized on government computer systems and is punishable under UCMJ?

The correct choice identifies personal blogging as not authorized on government computer systems and subject to punishment under the Uniform Code of Military Justice (UCMJ). This restriction is due to the potential for personal blogs to share sensitive or confidential information, compromise operational security, and violate the ethical standards expected of military personnel. Government computer systems are intended for official use, and activities like personal blogging can detract from this purpose, exposing individuals and the military to various risks.

In contrast, while personal email, online shopping, and social media use may also be discouraged or regulated, they do not carry the same explicit categorization of unauthorization as personal blogging does within the context of government computer systems. This distinction underscores the heightened concern over content that may be widely disseminated or believed to represent an official stance, which personal blogs can inadvertently do.