Final answer:
The STS serves as a contract between the Air Education and Training Command (AETC) and the functional user, outlining the division of training requirements for an AFSC that are covered in schooling and correspondence courses.
Step-by-step explanation:
The specialty training standard (STS) is an important contract within the United States Air Force that outlines the division of training responsibilities. The STS indicates which of the overall training requirements for an Air Force specialty code (AFSC) are covered in formal schooling and which are covered in correspondence courses. The correct answer to the question is a) Air Education and Training Command (AETC). This command is in charge of educating and training Air Force personnel, including the provision of technical training that would be stipulated under the STS. This formal agreement ensures that both the AETC and the functional user are aware of and agree on the training that is provided and what is expected of them.