Answer: the wage rate
Explanation:
The marginal resource cost for labor is the additional amount that a producer would have to pay to be able to get an additional worker to work under them and produce goods.
This is therefore the wage rate because it is the amount that the worker will be paid. This wage rate is determined by market forces in a competitive market which means that it is based on demand and supply; if more people are needed, the wage rate is higher and if less are needed, the wage rate is lower.
