Sales are 1,200 units sold at a price of $20 per unit. They are considering adding a chemical to each unit to allow for a longer shelf life (units will last longer) and thereby improving the product. Adding the chemical will allow them to sell each unit for $24; however, it will cost them $800 more per month to add the chemical. Operating income would decline by $800, increase by $4,800, increase by $4,000, or decline by $4,800.