Which of the following action will not release CO₂ into the air?

The major sources of carbon dioxide are-

• Respiration by humans and animals: all humans and animals take oxygen given by the plants and then release carbon dioxide into the atmosphere. 
• The burning of fossil fuels: They all produce carbon dioxide after combustion and that is why their excess use is a reason for global warming.
• While tree produces oxygen, so by planting a tree, oxygen enters the air.