Given the question: Read the following article and select the best answer. Article: If two scientists at Los Alamos National Laboratory are correct, people will still be driving gasoline powered cars 50 years from now, giving out heat-trapping carbon dioxide into the atmosphere--and yet that carbon dioxide will not contribute to global warming. In a proposal by two scientists, vehicle emissions would no longer contribute to global warming. The scientists, F. Jeffrey Martin and William L. Kubic Jr., are proposing a concept, which they have named Green Freedom, for removing carbon dioxide from the air and turning it back into gasoline. The idea is simple. Air would be blown over a liquid solution of potassium carbonate, which would absorb the carbon dioxide. The carbon dioxide would then be put to chemical reactions that would turn it into fuel : gasoline or jet fuel. This process could change carbon dioxide from an unwanted, climate-changing pollutant into a vast resource for renewable fuels. The cycle--equal amounts of carbon dioxide produced and removed--would mean that cars, trucks and airplanes using the synthetic fuels would no longer be contributing to global warming. Although they have not yet built a synthetic fuel factory, or even a small model, the scientists say it is all based on existing technology. "Everything in the concept has been built, is operating or has a close cousin that is operating." Dr. Martin said. The Los Alamos proposal does not go against any laws of physics, and other scientists who have independently suggested similar ideas. Dr. Martin said he and Dr. Kubic had worked out their concept in more detail than former proposals. There is, however, a major fact that explains why no one has built a carbon-dioxide-to-gasoline factory: it requires a great deal of energy. According to their analysis, their concept, which would cost about $5 billion to build, could produce gasoline at an operating cost of $1.40 a gallon and would turn economically practical when the price at the pump hits $4.60 a gallon. Other scientists said the Los Alamos proposal perhaps looked... Question: What is the concept of Green Freedom? - Removing the emission of carbon dioxide. - Reducing the carbon dioxide produced by car driving. - Recycling the carbon dioxide into gasoline. - Reserving the carbon dioxide for global warming.
The answer is:
Recycling the carbon dioxide into gasoline.