Answer:
b. Extrusive igneous rocks.
Explanation:
Extrusive rocks are rocks from magma that were thrown at Earth's surface while intrusive rocks are the ones from magma which were forced into rocks in the Earth’s crust.
When the lava and volcanic ash get to the surface, the rocks that are formed are extrusive igneous rocks.
In the 1960's the space industry developed in Florida, Alabama and Texas.
Hope this helps!
<3
Scientists can't determine because it's far to fragile and hot to dig into the earth therefore we don't know exactly how it is just can give an estimate based on what we already know from the other layers
