The answer is B-the concept of a unicameral legislature
In *2012 (I'm pretty sure that's what you're asking), Barack Obama was acting President of the United States of America.
Answer: Economic means relating to economics or the economy.
Opportunity cost means: The loss of potential gain from other alternatives when one alternative is chose
Scarcity means: The state of being scarce or in short or in short supply; shortage
Demand: an insistent and peremptory request, made as if by right
Supply: make something needled Ir wantsd available to someone;provided
Explanation:
THE Representatives of Spain and the United States signed a peace treaty in Paris on December 10, 1898, that established the independence of Cuba, ceded Puerto Rico and Guam to the United States, and allowed the victorious power to purchase the Philippines Islands from Spain for $20 million.