Answer:
a. Wheels are direct material cost as are essential for the automobile to complete, as the cars one of the main equipment is wheels as it will not work without wheels.
b. Glass used in vehicle's windows are also direct material cost, as the material is directly used in automobiles to complete it.
c. Wages are direct labor cost, as to make an automobile labor need to work on the process and assemble all the materials properly in the automobile and then they re paid wages in exchange.
