Marx's notion that societies go through inevitable stages of evolution is called:

The above figure shows the production possibility frontier for a country. Suppose the country is producing at point A. What is the opportunity cost of increasing the production of rice to 12 tons?

A) 6 thousand bottles of wine B) 9 thousand bottles of wine C) 15 thousand bottles of wine D) 12 tons of rice E) Nothing, it is a free lunch.

The table above shows sales of the firms in the chocolate industry. The four-firm concentration ratio in the industry is

A) 52 percent. B) 65 percent. C) 72 percent. D) 80 percent.