Duradyne, Inc. has total costs of S18,000 when 2,000 units are produced and $26,000 when 5,200 units are produced. During March, 4,000 units were produced and sold for S8 each. If the high-low method is used, how much is the variable cost per unit? . $2.50 . S0.40 C. $2.00 $4.00 D.