Question

crust describes the outermost shell of a terrestrial planet. earth’s crust is relatively thin, just 40 - kilometers (25 - miles) deep. earth’s crust can be divided into two types: continental and oceanic. which of these does not explain how these two types of crust differ?
a continental crust is thicker than oceanic crust.
b continental crust is less dense than oceanic crust.
c continental crust granitic composition: oceanic crust basalt and gabbro.
d continental crust enriched with fe and mg: oceanic enriched with al and si.
the core is made of two layers: the outer core, which borders the mantle, and the inner core. the inner core is shaped like a ball. iron and nickel in the outer core form an alloy, or a mixture of metallic elements. the outer core is approximately 2,300 kilometers thick and very hot, between 4,000 and 5,000 degrees celsius. the inner core is made mostly of iron. it is about 1,200 kilometers thick and extremely hot,
(image: diagram of earth’s layers labeled “lithosphere (crust and uppermost solid mantle)”, “mantle”, “core”, “not to scale”)

Explanation:

To solve this, we analyze each option:

• Option A: Continental crust (30 - 70 km) is thicker than oceanic crust (5 - 10 km), so this explains the difference.
• Option B: Continental crust (density ~2.7 g/cm³) is less dense than oceanic crust (density ~3.0 g/cm³), so this explains the difference.
• Option C: Continental crust is granitic (felsic, rich in Al, Si), oceanic is basaltic/gabbroic (mafic), so this explains the difference.
• Option D: Continental crust is rich in Al and Si, oceanic in Fe and Mg. This option reverses the composition, so it does NOT explain the difference.

Answer:

D. Continental crust enriched with Fe and Mg: oceanic enriched with Al and Si.