Why were early movies often called nickelodeon's

In which research method does a researcher change the value of one variable to determine how the change affects another variable? a. experiment b. observational research c. survey d. case study

An externality can be created by a. people working at a production job and enjoying their work b. a production activity but not a consumption activity c. a consumption activity but not a production activity d. a production activity or a consumption activity externalities a. are always positive, and an example is flu vaccinations b. are always negative, and an example is the pollution created by trucks c. can be negative or positive. logging has a negative externality, and education has a positive externality d. can be negative or positive. a negative externality is having to go to school when you would rather go to the beach, and a positive externality is spending time with your friends

Who built the first turnpikes in the united states? a) the national government b) state governments c) private companies d) town councils