Short description: A graph plots quantity of energy-efficient light bulbs in thousands against dollars per unit. Long description: The horizontal axis represents the quantity of energy-efficient light bulbs in thousands. The vertical axis represents dollars per unit. The graph plots three concave up increasing curves. The first curve representing S passes through the following points: a (100, 8), b (175, 9), c (225, 10), d (275, 11), and e (300, 12). The second curve representing S superscript 1 lies below and parallel to S. The third curve representing S superscript 2 lies above and parallel to S. FIGURE 3-2 Refer to Figure 3-2. If the supply curve is given by S, the ________ energy-efficient light bulbs is 175 000 when the price is $9. a. supply of b. supply schedule for c. quantity supplied of d. quantity sold of e. quantity purchased of