American Depositary Receipts (ADRs) allow U.S. investors to efficiently invest in foreign corporations without the need to trade on foreign exchanges. ADRs are traded on U.S. exchanges and represent shares of foreign companies.

D is correct because ADRs are designed for this purpose, simplifying currency exchange and reporting requirements for U.S. investors.

A is incorrect because directly purchasing an ETF on a foreign exchange requires additional steps, such as foreign account setup.

B is incorrect because options are derivative products, not direct investments in the stock.

C is less efficient because mutual funds may not provide direct exposure to the specific corporation.