Answer:
The correct answer is a. Drivers have a long or unlimited life span.
Explanation:
Value factors are internal or external variables that affect the value or general performance of the company at a given time. In this example, drivers are a limited workforce, since at a certain age they fulfill their legal work and must have a pension. This situation forces the company to replace people to ensure the normal level of operation, and that this does not influence the perception of customers about a deterioration in the service of drivers.