Exercise 2.13 why are there more earthquakes and volcanoes on one side of some continents than on the other? (a) are all continental coastlines plate boundaries? explain. (b). compare the west coast of south america with the west coast of africa. which has a broad continental shelf? a narrow shelf? which is close to an ocean trench? which coast would you expect to have the most earthquakes? explain.

Which of the following statements best characterizes changes to agriculture in the united states since 1900? a. increased mechanization has reduced the need for labor. b. increased mechanization has increased the need for water, thereby increasing the need for labor. increased mechanization has increased the use of land, thereby increasing the need for labor. d. increased mechanization has increased food production, thereby increasing the need for labor. select the best answer from the choices provided.