In 2000, the GDP of Canada was 1 trillion Canadian dollars. The exchange rate was 1 Canadian dollar per 0.69 U.S. dollars. What was the GDP of Canada in U.S. dollars? O a) 660 billion U.S. dollars O b) 670 billion U.S. dollars O c) 680 billion U.S. dollars O d) 690 billion U.S. dollars