Assume April was the month of the highest level of production, and August was the month of the lowest level of production. There were 2,000 units produced at a cost of $10,000 in April, and 1,000 units producd at a cost of $8,000 in August. Calculate the variable cost per unit using the high-low method. Select one: O a. $1.75 Ob. $2.00 c. $4.00 d. $3.00