The correct answer is      (B.)  First Solar (FSLR)

On December 31, 2007, shares of First Solar closed at $267.14 per share, but a year earlier, the stock was at a mere $29.84 per share. That incredible increase represented an almost +800% rise! But what exactly was behind this run-up?

Based in Phoenix, First Solar produces photovoltaic modules that produce clean, renewable energy. Many companies in this dynamic business are growing enterprises turning out real profits, and FSLR is leading the pack. Earnings at the firm have skyrocketed, and the stock has taken investors along for the ride.

But the ride might not be over yet. Currently, solar power accounts for just 0.1% of the nation's electricity, and the United States produces just around 500 megawatts of solar power each year. But by 2010, that total could easily reach 3,000 megawatts, and this translates into billions of potential revenues for companies like First Solar.

So, it's easy to see why these firms have attracted a wave of buying interest -- and the more than two dozen companies involved in the solar power field already have a combined market capitalization well in excess of $100 billion.

With all of this in mind, those looking to cash in on the bright long-term growth prospects of the alternative energy space might rush to buy up any alternative energy stock. But placing all your eggs in one basket by picking a single stock can be a costly endeavor. After all, if the fortunes of that firm turn, investors could be seeing red. Instead, smarter investors will consider one of the alternative-energy-centered funds highlighted in Nathan Slaughter's latest issue of The ETF Authority, including one fund that sports a shining +65% 1-year return! With extensive holdings and reasonable expense ratios, these ETFs are diversified opportunities to participate in one of the world's most transformative innovations. To read Nathan's article on alternative energy funds and to learn more about The ETF Authority newsletter, please visit this link.