Final answer:
Flow efficiency is the controllable metric that relates to Feature Driven Development (FDD), as it measures the effectiveness and consistency of feature development throughout the workflow.
Step-by-step explanation:
The controllable metric that ties into FDD (Feature Driven Development) is flow efficiency. This is because flow efficiency pertains to the smooth and continuous movement of features through the development process, from conception to delivery.
In contrast, delivery time measures the total time taken from the beginning of production to the delivery of the product, sorting accuracy relates to the precision with which items are categorized, and packaging quality refers to the condition and standards met by the packaging of goods. Flow efficiency is a critical measure in FDD as it optimizes the process by which a feature is developed, ensuring that efficiency is maintained throughout the workflow.