Question

why has the use of cfcs been phased out?
a. they cause acid rain.
b. they produce smog.
c. they destroy ozone molecules.
d. they impact the nitrogen cycle.

Explanation:

CFCs (chlorofluorocarbons) are known to break down ozone molecules. Acid rain is mainly caused by sulfur and nitrogen oxides. Smog is related to pollutants like volatile organic compounds and nitrogen oxides. The nitrogen cycle is impacted by various human activities but not directly by CFCs in the way ozone depletion is. Since CFCs' main harmful effect relevant to being phased - out is ozone destruction.

Answer:

C. They destroy ozone molecules.