The correct answer is      (B.)  PowerShares Global Water Portfolio (PIO)

That's right, for the last five years (through the end of last quarter), the Palisades Global Water Index has posted annualized returns of +24.9%, for a cumulative gain of +204% -- versus +160% for the S&P Global Water Index and just +44% for the S&P 500. In other words, a $10,000 investment made in 2003 would be worth more than $30,000 today.

Through PIO, shareholders can track the Palisades Global Water Index and have a stake in companies like Veolia Environment (NYSE: VE), the world's leading provider of water and wastewater treatment services. Other top holdings include Kurita, which supplies ultra-pure water for semiconductor manufacturing and makes reverse-osmosis seawater-desalination systems for remote islands; and Hyflux, a leading maker of water recycling technology used in Singapore and China. Overall, about 60% of the portfolio is in industrial companies; most of the rest is in water utilities.

Some consider water to be the single biggest infrastructure and commodity play, as this most precious of natural resources grows scarce and distribution systems in developed markets require billions in upgrades. In the U.S., as much as 40% of the country is being plagued by abnormally dry conditions, causing many regions to battle with wilting crops, lakes drying up, mandatory watering restrictions, and politicians arguing over control of dwindling supplies. And of course, the problem is global. Over the past century, the world's population quadrupled, but its water consumption ballooned +700%. UNICEF reports that a staggering 1.1 billion people lack access to safe drinking water. Clearly, there is a lot of work to be done.

It won't happen overnight, but oceans of money are about to be spent on water, and this presents incredible opportunities, as a handful of ETFs have been built with a single purpose: to assemble the planet's most promising water-related stocks in one place. In the latest issue of the ETF Authority newsletter, StreetAuthority editor Nathan Slaughter provides an in-depth look at this crucial industry and rates water-based ETFs in an effort to provide you with the best potential to capitalize on the coming sea change in the water business. To learn the names of these ETFs, and to learn more about the ETF Authority newsletter, please visit this link.