Science

dan described two layers of earth's atmosphere.

layer a: allows long-distance radio communication
layer b: separates outer space from earth's atmosphere

which statement is most likely true?

layer a is the thermosphere and layer b is the exosphere.
layer a is the exosphere and layer b is the thermosphere.
layer a is the troposphere and layer b is the stratosphere.
layer a is the stratosphere and layer b is the troposphere.