The ozone layer is at height of________kilometers from the surface of the Earth?
A. 10 to 20
B. 20 to 30
C. 30 to 40
D. 40 to 50
The ozone layer is at height of________kilometers from the surface of the Earth?
A. 10 to 20
B. 20 to 30
C. 30 to 40
D. 40 to 50