When we say the cost of production is $50, what is meant according to economic principles?
a. A firm had to spend $50 in order to purchase the resources required to make the good or service.
b. A value to society of this good or service was $50, so its cost is said to be $50.
c. A firm could have made something else with the resources that was worth $50 in the market.
d. $50 represents the maximum willingness to pay from market participants.