After Hiring Three New Employees, a Manager Sees That Total

After hiring three new employees, a manager sees that total output increases. If the manager hires two additional employees and discovers total output has fallen, the result is due to

A) diseconomies of scale.
B) a poor hiring procedure.
C) diminishing marginal returns.
D) the lack of skills of newest employees-the best workers are hired first.
E) economies of scale.