Darek Fidyka, a 38-year-old Bulgarian, had been paralyzed from the chest down for four years after a knife attack. Scientists from Britain and Poland took cells from his nose, transplanted them into his back and re-grew his spinal cord . Now he can walk and even drive a car. The doctors were delighted but said it was the first step in a long journey. The breakthrough came after 40 years of research by Professor Geoff Raisman, who found that cells had the possibility to repair damage to nasal nerves, the only part of the nervous system that constantly re-grows. "The idea was to take something from an area where the nervous system can repair itself and put it into an area that doesn't repair itself," Professor Raisman said. Polish doctors injected the nasal cells into Mr Fidyka's spinal cord above the injury and used some nerves from his ankle to form a bridge across the damaged tissue. The nasal cells appear to have caused the spinal nerves to repair themselves. Professor Raisman achieved this with rats in the late 1990's, but this is his greatest success. "I think the moment of discovery for me was Christmas in 1997 when I first saw a rat, which couldn't control its hand, put its hand out to me. That was an exciting moment, because I realized then that my belief that the nervous system could be repaired was true." Doctors chose the easiest case for their first attempt--it might not work for others. But there is a real sense of hope that an idea once thought impossible has been realized. David Nicholls, who helped provide money for the breakthrough, said information about the breakthrough would be made available to researchers across the globe. "What you've got to understand is that for three million paralyzed people in the world today, the world looks a totally brighter place than it did yesterday," he said. How did the operation work for Darek Fidyka? A) The nervous system in the spinal nerves can repair itself. B) The nerves from his ankle cured the patient of the injury. C) The nasal cells re-produced and spread over very quickly. D) The nasal cells helped the spinal nerves to repair themselves.
The answer to this question is:
D