Please choose the correct answer to the question: As the human population increases, more fossil fuels are being used. The burning of fossil fuels produces greenhouse gases. How might humans reduce greenhouse gases?

Answer1: Buy cars that use gasoline. Answer2: Build power plants that use coal. Answer3: Use renewable resources to generate power. Answer4: Use nonrenewable resources to generate power.

Answer format: answer1/answer2/answer3/answer4