The answer to this is D, if the rate of deforestation continues to increase.
In deforestation, trees and many plants may be removed. But the thing is, these plants are very important on keeping the suitable carbon dioxide and oxygen concentration in the atmosphere. Plants can undergo a reaction called photosynthesis, where carbon dioxide and water is absorbed and turned into oxygen, glucose (food for the plant) and energy. If the trees and plants are removed, photosynthesis rate would decrease and eventually more carbon dioxide and less oxygen will be found in the atmosphere.
On the other hand, all the other option can actually help the increase of carbon dioxide in the atmosphere. For example in A, riding bikes can reduce the amount of pollutants releasing to the air as the gas of vehicles contains carbon dioxide.
