The correct answer is      (E.)  Petroleo Brasileiro (PBR)

In December 2007, Petroleo Brasileiro (also known as Petrobras) announced the discovery of the Tupi oilfield off the coast of Rio de Janeiro, which has been estimated to contain as much as 30 billion barrels of oil. On top of this find, Petrobras has made several other discoveries recently, including the Jupiter gas field and the Carioca field -- both of which contain several billion more barrels.

Many believe Brazil will eventually overtake Venezuela as the most important oil producer in South America. This all may be startling news for some; after all, not everyone has heard of Petrobras, even though it carries a $300 billion market cap and is Brazil's national oil company (NOC).

NOCs are firms created by governments to manage local oil resources. In some cases, they are completely state-owned; however, in many countries governments have partly privatized these businesses, selling at least a minority stake to the public. Many are also listed as ADRs on the U.S. exchanges, allowing American investors a chance to profit from their growth.

Although foreign oil companies operate in Brazil, typically they must partner with PBR on deals. The partners provide much of the technology and know-how and receive a certain percentage of production from the project as compensation. Because NOCs control many of the world's best reserves, these partnership deals are frequently the only way for oil firms located in the U.S. to access promising foreign projects.

Investing in national oil companies is just one outstanding way to play the strong growth in global energy demand. They often have proven track records of weathering the inevitable downturns in the energy business, and as you can see with PBR, they have incredible potential. That's why StreetAuthority editor Paul Tracy dove into the oil business in the latest issue of his Market Advisor newsletter, offering an in-depth analysis of the industry and of specific oil stocks with solid growth prospects -- especially with crude nearing $140 a barrel. To learn the names of these stocks, and to learn more about the Market Advisor newsletter, please visit this link.