Answer:
diminishing marginal product of labor.
Step-by-step explanation:
The diminishing marginal product of labor theory states that as more of a variable production factor is increased there will initially be an increase in production.
However as more of the variable factor is added increase in production reduces until increase in variable factor results in decrease in production.
In the given scenario where Edith employs 3 baristas, an increase to 6 may yield lower productivity per unit of employee added