Bonita Industries has several outdated computers that cost a total $of$ $$15000$ and could $be$

sold $as$ scrap for $$6200.$ They could $be$ updated for $an$ additional $$2800$ and sold. $If$ Bonita

updates the computers and sells them, net income will increase $by$ $$9000.$

What amount $is$ considered sunk costs?

$$15000$

$$17800$

$$9000$

$$2800$