The correct answer in number one is "trees are cut down". Deforestation refers to the act wherein trees or forests are cut down and cleared for the land to be used for something industrial and non forest use.
In number two, the correct answer is "farming". Farming does not need deforestation. Farms are located in wide field, which has a huge land area for farming, which they do not need to clear trees/forests, sometimes farmers use the forests as parts of their farming methods.
In number three, the correct answer is "Carbon Dioxide". When trees begin to lessen, carbon dioxide will become greater in our atmosphere, since trees are the one responsible for absorbing and converting carbon dioxide to oxygen, without trees, it would increase the percentage of carbon dioxide in our atmosphere.
