Statements I and II accurately describe the U.S. dollar shortage during the great financial crisis. A dollar shortage is indeed a situation where a country lacks a sufficient supply of the U.S. dollar to effectively manage its international trade. This shortage can occur when a country has to pay more U.S. dollars for its imports than it receives from exports. The U.S. dollar acts as a 'safe haven' for other countries' currencies, and a shortage can have a significant impact on global trade. During the great financial crisis, many countries experienced this shortage, which exacerbated the economic downturn.

Choice B is incorrect. Statement III does not accurately represent the U.S. dollar shortage during the great financial crisis. The U.S. dollar shortage was not a result of mismatches between the maturity, currency, and counterparty of assets and liabilities but rather due to a sudden increase in demand for safe assets like U.S. dollars during times of economic uncertainty.

Choice C is incorrect. As explained above, statement III does not accurately represent the U.S. dollar shortage during the great financial crisis hence combination I, II and III cannot be correct.

Choice D is incorrect. Statements I and II do accurately represent aspects of the U.S. dollar shortage that occurred during the great financial crisis hence 'None of the above' cannot be correct.

Things to Remember

• Safe haven currency: The U.S. dollar is considered a safe haven currency, meaning that investors tend to flock to it during times of economic uncertainty or market turmoil.
• Impact on global trade: A U.S. dollar shortage can have significant implications for global trade, as countries may struggle to pay for imports or service their dollar-denominated debts.
• Foreign exchange reserves: Countries often hold U.S. dollars in their foreign exchange reserves to ensure they have an adequate supply of the currency for international transactions.
• Role of central banks: Central banks can intervene in foreign exchange markets to stabilize their currency's value or address shortages of foreign currencies like the U.S.