You are the manager of a firm that charges customers $61 per unit for the first five units purchased, $54 per unit for the next four units purchased, and $51 per unit thereafter.Your firm's marginal cost and average total cost are constant at $45.If the consumer purchases 14 units, what is your firm's profit?

Group of answer choices

None of the answers listed is correct.

$146

$139

$175

$162