You need to buy some filing cabinets. you know that cabinet x costs $10 per unit and requires six square feet of floor space. cabinet y costs $20 per unit and requires eight square feet of floor space. you have been given $140 for this purchase, though you don't have to spend that much. the office has room for no more than 72 square feet of cabinets. cabinet x provides 8 cubic feet of storage, and cabinet y provides 12 cubic feet of storage. how many units of each model should you buy to maximize storage space? a) 0 units of cabinet x, 7 units of cabinet y b) 12 units of cabinet x, 0 units of cabinet y c) 3 units of cabinet x, 8 units of cabinet y d) 8 units of cabinet x, 3 units of cabinet y