Which of the following is not an argument usually presented in favor of trade restrictions?

In the long run

A) fixed costs tend to be greater than variable costs. B) variable costs tend to be greater than fixed costs. C) all costs are fixed costs. D) all costs are variable costs.

This table shows the total costs for various levels of output for a firm operating in a perfectly competitive market.PriceQuantityTC$500$10.00$501$20.00$502$27.50$503$77.50$504$147.50$505$250.00According to the table shown, what is the firm's marginal cost from producing the 2nd unit?

A. $20.00 B. $10.00 C. $7.50 D. $27.50