Please choose the correct answer to the question: Carbon dioxide emissions have increased due to large numbers of automobiles and increased industrialization. Which of the following has been most affected by the increase in carbon dioxide levels?

Answer1: the ability of farmers to plant crops Answer2: the ability of scientists to study other planets Answer3: the ability of Earth to continue recycling rocks Answer4: the ability of Earth to maintain lower temperatures

Answer format: answer1/answer2/answer3/answer4