What AFI outlines AFSC upgrade training requirements for skill levels?

The correct choice is B because DAFI 36-2670 specifically details the Force Development framework within the Air Force, which includes instructions on career development and the training requirements for various Air Force Specialty Codes (AFSC) at different skill levels. This directive is essential for understanding how personnel can successfully progress through their respective career fields, meeting the necessary training and upgrade requirements that are vital for maintaining a skilled and effective force.

The other options, while being relevant Air Force instructions, do not address AFSC upgrade training requirements directly. For example, AFI 36-2903 primarily focuses on dress and appearance standards; AFI 36-2656 is concerned with the management of training programs; and AFI 36-2626 details the development and management of the enlisted promotion system. Each of these addresses different aspects of Air Force policy and procedure but does not specifically cover the training requirements for upgrading AFSC skill levels as outlined in DAFI 36-2670.