Which of the Following Companies Has a Competitive Advantage

Which of the following companies has a competitive advantage?

A) Netcentives is trying to acquire the patent on a software that allows merchants to distribute loyalty points on-line.
B) Mildred's Café makes the world's best pecan pie according to one survey.
C) DeBeers diamonds used to control 90 percent of the world's diamond mines.
D) World Wrestling Entertainment (formerly the World Wrestling Federation) holds the trademark on the names of the wrestlers who participate in the company's wrestling matches.