A certain firm can sell as many units of its product as it wishes at a market price of $30 per unit. The firm's total cost of producing various quantities is shown in the accompanying table. IN order to maximize its profit, this firm should sell ____unit(s).

A) 8

B) 5

C) 6

D) 4

E) 7

 

Unit - 12 3 4 5678 Total Cost $40 60 78 98 120 148 184 240