Concept:Productivity is the amount of output produced per unit of input in a given time. In a working environment the input usually measured is labour.Solution:Productivity of labour = total output ÷ number of workers, that is, output per worker.Output of the country (A) is national output (GDP), not productivity. Management of workers (B) and quantity of resources (D) are not measures of productivity.Answer:Option C (output per worker)