Concept:The Earth’s structure from the surface downward consists of the crust, mantle, and core.
Explanation:The crust has two parts: the upper continental crust is made of silica and aluminium, called
sial.
The lower oceanic crust is richer in silica and magnesium, called
sima.
Below the crust lies the
mantle.
At the centre is the
core.
Therefore, moving from the surface to the interior, the order is sial, sima, mantle, core.
Answer:D. sial, sima, mantle and core.