The cost to manufacture one unit of Rinker Audio Products' bestselling hearing aid, the Magnifier, is $87.50. The CFO of the company, Neha Patel, has determined that if the company expands the output of its biggest U.S. plant by 20 percent, the unit cost would be only $82.50. The concept that as plant output expands, unit costs decrease, is known as
A. minimum efficient scale.
B. lean production.
C. Six Sigma.
D. economies of scale.
E. total quality management.
Answer: D. economies of scale