Question

Increasing the use of nuclear power and planting trees in urban areas are two methods of reducing atmospheric levels of what gas? carbon dioxide ozone cfcs sulfur dioxide

Answer 1

Increasing the use of nuclear power and planting trees in urban areas are two methods of reducing atmospheric levels of : Carbon dioxide

If it used correctly, the energy that produced with nuclear power does not produce harmful emission for the environment such as CO2.
As for trees, they absorb CO2 for their photosynthetic process, which will reduce CO2 amount in atmosphere