Ashlee Patterson, a student of economics, argues that product differentiation by these firms will reduce economic welfare. However, Tony Prescott, her friend, disagrees. According to Tony, social welfare will increase because consumers now have more choices. While claiming that social welfare will increase because consumers now have more choices Tony is ignoring the fact that: A. product differentiation allows firms to enjoy monopoly power. B. producer surplus increases when firms differentiate their products from what their rivals offer. C. different people have different preferences. D. efficiency under monopoly is lower than efficiency under monopolistic competition. E. firms selling identical products face perfectly elastic demand curves.