The correct answer is      (B.)  2.2 Billion

Over the past four years, Berkshire Hathaway has pocketed about $2.2 billion in profits from direct foreign currency forward contracts, mostly on the euro ($839 million), Canadian dollar ($398 million), and British pound ($287 million).

Foreign exchange can be a complicated concept, but if you have traveled abroad recently, then you probably understand the impact of a weaker dollar when it comes to purchasing power. In early 2002, it took about $0.83 to buy one euro -- now it will cost you about $1.40. In other words, the same 200-euro per night Paris hotel room that cost $166 five years ago will now set you back about $280.

But what's bad news for the U.S. traveler can be great news for the U.S. investor. And you don't have to invest in complex, risky currency forwards and other derivatives as Buffett did to take advantage of these market conditions.

For example, stocks of U.S. multinationals, which get a boost when a falling dollar makes their products more competitively priced in foreign markets, can be good investments. Meanwhile, securities denominated in foreign currencies can make big gains, even if there is no share price appreciation, simply due to the change in the exchange rate. There are also dollar-denominated commodities such as crude oil, corn, or copper. They post gains when the greenback deteriorates because dollar-denominated commodities become more attractive to foreign investors holding stronger currencies. It's no coincidence that as the dollar has plunged, gold has soared to near $800 per ounce, and crude has gone above the $90 per barrel mark.

But by far the easiest way to profit from the falling dollar is with exchange-traded or closed-end funds focused on firms that benefit from the dollar's decline. After all, you can invest in a single multinational firm, but if an accounting scandal or some other calamity hits that company, your exposure could cost you serious money. Meanwhile, investing in individual foreign securities can be a difficult and expensive task for domestic investors.

However, funds offer a way to diversify across many securities -- this limits your exposure to just one company -- and they also offer a simple, inexpensive way to buy stock in foreign firms.

And Nathan Slaughter, editor of StreetAuthority's ETF Authority newsletter, has studied the options and unearthed six funds that are great starting points for investors looking to capitalize on the continued decline of the dollar. This includes one fund trading at a 7% discount to its net asset value (NAV) -- that means you can pick up a dollar's worth of portfolio assets for just 93 cents. Meanwhile, the same fund also yields an tantalizing 7%. To see Nathan's entire list, as well as in-depth profiles of his two favorites, you have to be a subscriber. If you would like to learn more, please visit this link.