A console game, ZOMBIES!, has come out recently. It sells for $60. Which of these might lower the price of the game?
a)A negative article about the game from a well-known reviewer, causing sales to drop
b)A positive article about the game from a well-known reviewer, causing sales to rise
c)A significant increase in the cost of a competitor's game, U.S. Zombies
d)A significant rise in the cost of gas, causing shipments of the game to slow down