The Above Table Shows the Quantity of Patents Reviewed by a Firm's

The above table shows the quantity of patents reviewed by a firm's attorney and the corresponding probability that the firm w infringe on another firm's patent. The cost of infringement is $50,000.
-Refer to the table above. If the attorney reviews 53 patents, what is the expected marginal benefit of reviewing the 53rd patent?

A) - $20,000
B) $20,000
C) - $2,000
D) $2,000