What is permanent working capital? A. the amount that a firm must keep invested in its short - term assets to support its continuing operations B. the difference between the actual level of investment in short - term assets and the amount that a firm must keep invested in its short - term assets to support its continuing operations C. the amount that a firm keeps invested in its short - term assets to support its continuing operations which are financed by short - term debt D. the amount that a firm keeps invested in its short - term assets to support its continuing operations which are financed by long - term debt