For the Following Issue, Discuss Which Source You'd Trust More

For the following issue, discuss which source you'd trust more, and give at least one reason why. You may want to add to or otherwise modify our list of sources. And do keep in mind that we are glad our livelihoods do not depend on a general consensus on our rankings.
Issue: Do violent video games contribute to increased aggressiveness in players?
a. the president of the Entertainment Software Association
b. a long-time video game player
c. a university researcher who studies the link between video games and violence
d. parents of teens who play video games