Tally Corp. sells softwares during the recruiting seasons. During the current year, 11,000 softwares were sold resulting in $440,000 of sales revenue, $110,000 of variable costs, and $48,000 of fixed costs. If sales increase by $60,000, operating income will increase by ________.

a. $40,000

b. $60,000

c. $45,000

d. $10,000

e. one of the above.