​Corporation, a manufacturing​ company, is analyzing its cost structure in a project to achieve some cost savings. Which of the following statements​ is/are correct? I. The cost of the direct materials in Applewhite​'s products is considered a variable cost. II. The cost of the depreciation of Applewhite​'s plant machinery is considered a variable cost because Applewhite uses an accelerated depreciation method for both book and income tax purposes. III. The cost of electricity for Applewhite​'s manufacturing facility is considered a fixed​ cost, even if the cost of the electricity has both variable and fixed components