Routsong Company had the following sales and production data for the past four years:

Year1 Year2 Year3 Year4
Production in units..... 6,000 9,000 4,000 5,000
Sales in units.............. 6,000 6,000 5,000 7,000

Selling price per unit, variable cost per unit, and total fixed cost are the same in each year. Which of the following statements is not correct?

a. Under variable costing, net operating income for Year 1 and Year 2 would be the same.
b. Because of the changes in production levels, under variable costing the unit product cost will change each year.
c. The total net operating income for all four years combined would be the same under variable and absorption costing.
d. Under absorption costing, net operating income in Year 4 would be less than the net operating income in Year 2.