Dquestion 9 1 pts the oceanic ridge system is the major site of spreading center volcanism. o formation of magma by partial melting of mantle rocks. formation of basaltic magma. all of these both spreading center volcanism and formation of magma by partial melting of mantle rocks. 1 pts d question 10

Volcanic irruption is most likely to be violent when a) volcanoes near to the sea b) the neck of the volcano is sealed by a plug c) the lava is viscous d) the lava reaches the surface through a fissure e) the volcano is on the ocean floor

Where does the availability of water pose the greatest problem

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.