If sales totaled $200,000 for the current year (10,000 units at $20 each) and planned sales totaled $150,000 (12,500 units at $12 each), the effect of the unit price factor on the change in sales is a:
Select one:
a. $80,000 increase
b. $20,000 decrease
c. $30,000 increase
d. $30,000 decrease