Dybala Corporation's produces and sells a single product. Data concerning that product appear below:

	Per Unit	Percent of Sales
Selling Price	$150	100%
Variable Expenses	60	40%
Contribution Margin	$90	60%

The company is currently selling 5,900 units per month. Fixed expenses are $474,700 per month. The marketing manager believes that a $6,900 increase in the monthly advertising budget would result in a 100 unit increase in monthly sales. What should be the overall effect on the company's monthly net operating income of this change?

a. Decrease of $2,100

b. Increase of $9,000

c. Decrease of $6,900

d. Increase of $2,100