单选题 " The utilities are more interested in protecting their stranglehold on the power grid and preserving their century-old business model than they are producing clean electricity," says Jim Harvey, who heads up the Joshua Tree, Calif. — based Alliance for Responsible Energy Policy, an advocacy group that's staunchly opposed to utility-generated solar power. Harvey actually believes that the country's entire renewable portfolio can be achieved through rooftop solar alone. That may be possible from a sheer megawatts perspective, but from a practical standpoint, it's way over— ambitious. With no centralized source, how do you run traffic or street lights? What if it rains for a week? We still don't have foolproof means to store solar power, so for how, distributed generation needs the grid as a backup.
What does the author think of Harvey's idea of achieving the country's entire renewable portfolio through rooftop solar alone?

• A. It is possible.
• B. It is not practical.
• C. It is out of question.
• D. It takes time to se