2 point Table 4-5 Price Firm A's Firm B's Firm C's Firm D's Quantity Quantity Quantity Quantity Supplied Supplied Supplied Supplied 0 0 $2 4 - IN $4 8 4 56 9 12 6 SB 12 16 $10 15 20 10 Refer to Table 4-5. If these are the only four sellers in the market, then when the price increases from $4 to $6, the market quantity supplied O a. increases by 20 units. O) b. decreases by 10 units. O c. decreases by 20 units. O d. increases by 10 units