Answer:
b) Nothing, because you are already minimizing cost
Step-by-step explanation:
cost of producing one additional unit by hiring more workers = $10 / 50 units = $0.20 per unit
cost of producing one additional unit by buying the machine = $200 / 1,000 units = $0.20 per unit
Since labor exhibits a diminishing return, the next unit of labor will produce less than 50 units. This means that if you want to increase production, you should buy the machine.
Using the same logic, the previous units of labor were able to produce more than 50 units, which means that the average total cost was lower using labor than the machine. So if the company's concern is to minimize costs, then they are already doing so.