9. Classify the total costs of each of the following as variable, fixed, mixed, or step. Sales volume is the cost driver. a. Wages of machine operator who is paid based on number of units produced on the machine b. Keyboards purchased from a subcontract supplier in a computer assembly plant Property taxes d. Salaries of quality inspectors when each inspector can evaluate a maximum of 500 units per day e. Annual salary for the vice president of manufacturing f. Electric power in a factory g. Raw materials used in production h. Water consumed by the plant, which is based on a flat fee plus actual consumption i. Overhead costs in the factory for incidental components such as small screws and rivets. j. Fire insurance on factory building