Question

use of chemicals called chlorofluorocarbons, or cfcs, has caused levels of ozone in the ozone layer to

o increase
o decrease
o remain steady

Explanation:

Chlorofluorocarbons (CFCs) are known to break down ozone molecules. When CFCs reach the stratosphere, they release chlorine atoms. These chlorine atoms react with ozone ($O_3$) to form oxygen ($O_2$) and chlorine monoxide ($ClO$). This process reduces the amount of ozone in the ozone layer.

Answer:

decrease