Productivity measurement is complicated by

Productivity measurement is complicated by the fact the precise units of measure are often unavailable. When you are managing productivity it can vary based on each task or the person completing the tasks. Because of this, it makes it complicated for management to measure productivity as there could be no units or no comparable units to measure. Productivity is better reflected on the outcome of what they do complete versus what they do not. 

If its a multiple choice test, then it should be a conservationist.