Final answer:
Cost drivers have the strongest cause and effect relationship with overhead costs since they are the factors that cause overhead costs to change. They are directly linked to variable input costs, such as labor and raw materials.
Step-by-step explanation:
Among the options provided, the element that should have the strongest cause and effect relationship with overhead costs is C. Cost drivers. Cost drivers are factors that cause costs to increase or decrease.
Variable costs, which are part of overhead costs, increase or decrease with output level, as they are associated with variable inputs such as labor and raw materials. More workers or work hours are required to produce a greater quantity of goods or services, which are variable costs.
Similarly, more raw materials would be needed, which are also variable costs. Units of output also have a direct relationship with overhead costs; however, they are the result, not the driver, of the costs.