Cut-Ups is a barbershop where the barbers tell jokes as they cut customers' hair. Recently, someone has been posting anonymous online reviews claiming that Cut-Ups gives terrible haircuts and that the barbers' jokes are not funny. Cut-Ups might be able to file a lawsuit for defamation if which of the following is true?

a. A professional comedian writes its jokes.
b. All of its previous online reviews have been positive.
c. It can prove the person posting the comments has never been a customer at the shop.
d. It can prove the customer posting the reviews is related to a barber at another barbershop.