According to the APICS CSCP - Supply Chain Management Certification, a free trade zone (FTZ) is a designated area within a country where goods can enter, undergo further modification, and then be exported without paying customs duties or taxes. FTZs are used to encourage foreign trade and investment, reduce transportation costs, and improve supply chain efficiency.

To achieve economies of scale, manufacturers need to produce large quantities efficiently. Inventory functions that balance supply and demand help manage this process by ensuring that production output aligns with market needs. This function allows manufacturers to plan production schedules that maximize capacity utilization while minimizing stockouts and overproduction. Geographical specialization (A) relates to the allocation of production across different locations, decoupling (B) refers to separating production processes to maintain flow, and buffering uncertainty (D) addresses variability in supply and demand, but balancing supply and demand is the key to achieving economies of scale through synchronized production and consumption rates.
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Chopra, S., & Meindl, P. (2016). Supply Chain Management: Strategy, Planning, and Operation. Pearson.
Stevenson, W. J. (2018). Operations Management. McGraw-Hill Education.