Table 4-4 Price Quantity Supplied (Units) (Dollars per unit) Firm A Firm B Firm C Firm D 0 0 0 0 0 2 2 3 4 5 4 4 6 8 10 6 6 9 12 15 8 8 12 14 20 10 10 15 16 25 Refer to Table 4-4. If these are the only four sellers in the market, then when the price increases from $6 to $8, the market quantity supplied a. decreases by 4 units. b. increases by 12 units. c. increases by 0.5 units. d. increases by 2 units