The University Store, Incorporated is the major bookseller for four nearby colleges. An income statement for the first quarter of the year is presented below: University Store, Incorporated Income Statement For the Quarter Ended March 31 Sales $ 800,000 Cost of goods sold 560,000 Gross margin 240,000 Selling and administrative expenses Selling $ 100,000 Administrative 110,000 210,000 Net operating income $ 30,000 On average, a book sells for $40.00. Variable selling expenses are $3.00 per book; the remaining selling expenses are fixed. The variable administrative expenses are 5% of sales; the remainder of the administrative expenses are fixed. The net operating income computed using the contribution approach for the first quarter is:

a.$180,000

b.$30,000

c.$0

d.$120,000