it is the crust because the crust is thin and rigid with rock
outer core
The Lithosphere
mantle
If there were such a thing it would not be soft, it would be liquid, and would be called magma. There really is no completely molten layer of Earth except for the outer core which is composed primarily of liquid iron along with some nickel and other trace elements.
Tectonic plates float on an underlying molten layer.
The rigid, rocky layer of the Earth is called the lithosphere.
The rigid layer of earth surrounding the asthenosphere is the lithosphere.
it is the crust because the crust is thin and rigid with rock
A substance can't be rigid and molten. I wonder if you are confused by the lower mantle, also called the asthenosphere, which is not molten but can flow. In any case the layers are:The crust, which is solid rock and therefore rigid, though of course sufficient force will deform or fracture it.The mantle, which is essentially solid though the lower parts can flow much like asphalt under extreme pressure.The outer core, which is liquid iron and nickel.The inner core, which is solid iron and nickel.
The outer core is the only molten layer of the Earth. == ==
crust
you
The rigid layer that is the upper mantle and crust is called the lithosphere.
The outermost rigid layer of the earth is called the crust.
The asthenosphere.
core