Cardinal uses the high-low method of estimating costs. Cardinal had total costs of $25,000 at its lowest level of activity, when 5,000 units were sold. When, at its highest level of activity, sales equaled 10,000 units, total costs were $39,000. Cardinal would estimate variable cost per unit as:a. $3.52
b. $3.30
c. $2.60
d. $3.93