Raruanian Enterprises has started producing all-natural ingredients to use in cosmetic lines. Current monthly 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 $4800 increase by $4000 no