Final answer:
Supplements are used to consolidate instructions from various levels into one single directive, ensuring a comprehensive and unified set of instructions. The FAA Order JO 7110.65, for example, uses supplements to compile updates and changes.
Step-by-step explanation:
The document used to consolidate instructions from different levels into a single directive to avoid having instructions scattered among several directives is C. Supplements. Supplements are typically used in organizational settings, like the Federal Aviation Administration (FAA), to compile various orders, notices, and changes into one comprehensive document.
This helps in maintaining clarity and consistency in the instructions being given, ensuring all personnel have access to the same unified information. FAA Order JO 7110.65 is an example of a specific document that prescribes air traffic control procedures and phraseology for use by personnel providing air traffic control services in the United States.
This order is periodically updated with changes and supplemented with notices or other directives. However, it is specifically the supplements that collate all necessary amendments and instructions into one, avoiding the scattering of directives.