Concept:The Earth's solid outer shell is the lithosphere, which includes the crust and the rigid upper mantle.
Explanation:The lithosphere is the coolest, most rigid rocky layer of the Earth.
It consists of the crust and the outermost part of the upper mantle.
There are two types: oceanic lithosphere (denser) and continental lithosphere.
Tectonic activity occurs here.
The hydrosphere is all water on Earth, not a solid shell.
The troposphere is the lowest atmospheric layer.
The crust alone is only the very top layer; the lithosphere is the entire solid outer shell.
Answer:D. Lithosphere