Minden Co has current assets of $180,000 (cash: $20,000, accounts receivable: $70,000, inventory: $90,000), and long-term assets that had to cost $400,000, with accumulated depreciation to date of $180,000. Sales were $500,000, and operating profit was $50,000. Tax was $20,000 and interest paid was $10,000. Their inventory holding period (to the nearest day) was: a) 66 days b) 51 days c) 46 days d) 32 days e) none