The answer is option "a", "functional decomposition diagrams (fdd)".
The purpose behind the functional decomposition diagram is to appear on a single page the capacities of an association that are significant to the thought of a design. By analyzing the abilities of an association from a useful point of view, it is conceivable to rapidly create models of what the association manages without being dragged into a broadened debate on how the association does it. Once a fundamental functional decomposition diagram has been produced, it winds up noticeably conceivable to layer heat-maps over this outline to demonstrate extension and choices. For instance, the capacities to be actualized during the diverse periods of a change program.