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