(Table: Variable Costs for Lots) Use Table: Variable Costs for Lots.During the winter,Alexa runs a snow-clearing service in a perfectly competitive industry.Assume that costs are constant in each interval;so,for example,the marginal cost of clearing each of the lots from 1 through 10 is $20.Also assume that she can only plow the quantities of the lots given in the table (and not numbers in between) .Her only fixed cost is $1,000 for a snowplow.Her variable costs include fuel,her time,and hot coffee.If the price to clear a lot is $60,what is Alexa's profit or loss at the optimal output?

A) $3,000
B) $1,100
C) $900
D) $3,850

To find the optimal output, Alexa needs to keep producing as long as her marginal cost is less than or equal to the market price of $60. We can see from the table that at the quantity of 30 lots (between lots 21 and 31), Alexa's marginal cost equals $57, which is less than the market price of $60. So she should produce 30 lots.

To calculate profit, we need to subtract total costs (fixed cost + variable costs) from total revenue (price per lot times the quantity of lots produced).

Total revenue = $60 x 30 lots = $1,800
Variable costs = $17 x 30 lots = $510
Fixed cost = $1,000
Total costs = $1,510

Profit = Total revenue - Total costs = $1,800 - $1,510 = $290

Therefore, Alexa's profit at the optimal output is $290, which is option C.