Question

select the best answer for the question.

diagram labels: oceanic crust, trench, volcanic arc, continental crust, lithosphere, asthenosphere

1. what can you conclude about the oceanic crust in the image?

○ a. it exerts no upward force on the continental crust.
○ b. it sits at a higher elevation than the continental crust.
○ c. it’s denser than the continental crust.
○ d. it’s composed mostly of granitic rock.

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Explanation:

• Option A: The oceanic crust is subducting, but it still interacts with the continental crust, so it exerts forces. Eliminate A.
• Option B: Oceanic crust is under the ocean and continental crust is above sea level in the image, so oceanic crust is at lower elevation. Eliminate B.
• Option C: Oceanic crust (composed of basaltic rock) is denser than continental crust (composed of granitic rock), which is why it subducts. This matches the subduction shown.
• Option D: Continental crust is mostly granitic; oceanic is basaltic. Eliminate D.

Answer:

C. It's denser than the continental crust.