Answer: A) it makes a statement about them
Let's be honest: part of the success of the Toyota Prius is the fact that it has come to symbolize efficient, green, responsible living. That's why Honda discontinued its Honda Accord hybrid: because people couldn't easily identify it as a hybrid, sales were far lower than the Prius, which is only sold as a hybrid. Without a doubt, Prius owners take into account gas prices, carbon emissions and the feel of the car, but more than half of them recognized that, above all else, it was a statement about their values.
Source: Ready, Set, Green page 100