(5-1) If variable selling and administrative expenses totaled $124,000 for the year (80,000 units at $1.55 each) and the planned variable selling and administrative expenses totaled $136,500 (78,000 units at $1.75 each), the effect of the quantity factor on the change in variable selling and administrative expenses is:

a. $3,500 decrease.

b. $3,000 decrease.

c. $3,000 increase.

d. $3,500 increase.