Concept:The Earth is made up of several concentric layers, and the question asks for the name of its outermost solid layer.
Explanation:The Earth's interior is divided into distinct layers: the crust, mantle, outer core, and inner core.
The crust is the thin, solid, outermost layer of the Earth.
It is the layer on which we live and it includes both the continental crust and the oceanic crust.
The mantle lies directly beneath the crust and is much thicker and denser than the crust.
The barysphere refers to the innermost part of the Earth, mainly the core, so it is not the outer layer.
A hemisphere is half of the Earth's surface, used in geographical divisions, and is not a layer of the Earth at all.
Therefore, the outer layer of the Earth is correctly called the crust.
Answer:The correct option is A. crust.