The economic concept that Zane's production process best characterizes is Diminishing marginal productivity.
Diminishing marginal productivity is the economic concept that using an increasing amount of variable inputs while holding other inputs constant (fixed inputs) leads to decreasing productivity.
For example, the employment of an additional worker by Zane when capital is held constant decreases the marginal product of labor by 5 units.
Thus, the economic concept that Zane's production process best characterizes is Diminishing marginal productivity.
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