Price Ob. 28 units. Oc. 7.5 units. Od. 10 units. (Dollars per unit) 0 2 4 6 8 10 Table 4-4 Firm A 0 2 4 6 8 10 Quantity Supplied (Units) Firm B Firm C 0 3 6 9 12 15 0 4 8 12 14 16. Firm D 0 SASOS 5 10 15 20 25 Refer to Table 4-4. If these are the only four sellers in the market, then the market quantity supplied at a price of $4 is Ca. 4 units.