If substantial batch-level or product-level costs exist, then overhead allocation based on a measure of volume such a dec O is a key aspect of the activity-based costing model. O will systematically overcost low-volume products and undercost high-volume products will systematically overcost both high-volume products and low-volume products O will systematically undercost both high-volume products and low-volume products O will systematically overcost high-volume products and undercost low-volume products