(Table: Variable Costs for Lawns) Look at the Table Variable

(Table: Variable Costs for Lawns) Look at the table Variable Costs for Lawns.During the summer Alex runs a lawn-mowing service, and lawn-mowing is a perfectly competitive industry made up of 100 identical firms.The table shows his variable costs for lawn-mowing and the number of lawns mowed.Alex's fixed cost is $1,000 for the mower.His variable costs include fuel, his time, and mower parts.If the price for mowing a lawn is $70, how much is Alex's profit per unit at the profit-maximizing output?
A.-$10
B.$10
C.$34
D.$14