13.Refer to Exhibit 3-3. A movement from point Z to point Y would have been the result of 6 Praco (dollars) 1- 2 D : Quantity a price reduction. an increase in population. O an increase in income. O a positive change in tastes.18. Refer to Exhibit 3-4. If this is a competitive market, price and quantity will gravitate toward S A Price (dollars) D 15 20 quantity O $6 and 10 units, respectively. O $6 and 20 units, respectively. $4 and 15 units, respectively. $2 and 15 units, respectively.19. Refer to Exhibit 3-8. A shortage exists at any price below: * 3 Price (dollars) 2 10 15 20 25 20 Quantity $4.50. $4.00. $3.50. O $3.0035. Refer to Exhibit 21-4. Curve A is a(n) cost curve. * Cost A - D Quantity of Output O marginal O average variable O average total average fixed36. Refer to Exhibit 227. The short run supply curve of this perfeotl competitive rm starts at what level of output? tars} Price and Cast {o D _I-I\\~n.hli1~n.h1 at} U II] 2-] 3:} 4D SCI I50 T Quantity