What is the economic term for what you lose when using resources for something else?

Ineed with number 17 i don’t get it at alll

The technique of getting a commitment from a potential customer and then changing the terms of the agreement is best described as low-balling. cognitive dissonance. reciprocal concession. the foot-in-the-door technique. a half-dozen high school students are going to a concert. chantal wants to wear a new colorful outfit that she just received as a gift, but she assumes that her five friends will all be wearing nothing but black leather. chantal decides to do likewise, and leaves her colorful outfit in the closet. chantal’s behavior is an example of conformity. resistance. reciprocation wariness. idiosyncrasy credits.

What word means having a variety of cultures in the same area? a. cultural diversity b. culture region c. popular culture d. population density