Item 18 Which word is described by this statement?

Scientists use this to measure the magnitude of an earthquake.

shield

magma chamber

Richter scale

seismograph

Can someone read this article and tell me the 1) key ideas and 2) one key quote (copy and paste the link the article is not to long at all)from

In the kingdom of saudi arabia the government controls every aspect of oil production which makes up the majority of the country's economy. while other businesses are owned by individuals, the biggest segment of saudi arabia's economy is oil production. saudi arabia's economy would best be described as a) entirely market. b) almost entirely command. c) a mixture between just market and traditional. d) a mixed economy with large amounts of command.

Suppose you are a freshmen in college and you have not declared a major. one reason you enrolled at your respective college was the school's vibrant social life. at the same time, you want to balance your academic life because you know that your grades will matter for graduate school or job applications. you decide to forgo partying for two hours to study for an upcoming economics exam. in your first semester's principles of economics class, you learn that the enjoyment you would have received from partying is an example of a(n)