An action such as unit activation, inactivation, redesignation, or variation to a standard structure requires a(n) _______________.

The correct answer is Organizational Change Request (OCR) because this document is specifically designed to manage and formalize changes within an organization, including actions like unit activation, inactivation, redesignation, or modifications to an existing standard structure. An OCR outlines the proposed changes, justifications, impacts on the organization, and tracks the approval process.

This process ensures that any modifications are examined thoroughly, allowing for a structured approach to organizational development and resource allocation. Consequently, it helps maintain organizational readiness and efficacy during transitions, making the OCR vital for formalizing these types of changes.

The other options do not encompass the formalities or the broad scope needed for such organizational changes. For instance, a Personnel Change Notification mainly deals with changes related to staffing and individual personnel actions rather than broader organizational adjustments. A Unit Activation Form typically focuses on the specific procedures to activate units, while a Mission Change Order pertains to changes in mission directives rather than structural changes within the organization. Thus, OCR is the most appropriate choice for this context.