________ is a problem that occurs when one concludes that a change in variable X caused a change in variable Y when in actual fact, it is a change in variable Y that caused a change in variable X

When making a choice to do more of one activity, the highest-valued other choice society does not make is called _______ , and it is measured _______ .

A) opportunity cost; in terms of the money it costs B) increasing cost; in terms of the amount of money spent doing so C) constant cost; by the slope of the production possibilities curve at that level D) opportunity cost; by the slope of the production possibilities curve at that level

Abstracting from reality is an important element of all economic models

a. True b. False Indicate whether the statement is true or false