Passage OneQuestions 52 to 56 are based on the following passage.Amid all the job losses, there’s no category of worker that the economic disruption has been good for: nonhumans.From self-service checkout lines at supermarket to industrial robots armed with saws and taught to carve up animal bodies in slaughter-houses, these ever-more-intelligent machines are now not just assisting workers but actually kicking them out of their jobs.Automation isn’t just affecting factory workers, either. Some law firms now use artificial intelligence software to scan and read mountains of legal documents. work that previously was performed by highly-paid human lawyers."Robots continue to have an impact on blue-collar jobs, and white-collar jobs are under attack by microprocessors," says economics professor Edward Learner. The recession permanently wiped out 2.5 million jobs. US gross domestic product has climbed back to pre-recession levels, meaning we’re producing as much as before, only with 6% fewer workers. To be sure, robotics are not the only job killers Out there, with outsourcing（外包）stealing far more jobs than automation.Jeff Burnstein, president of the Robotics Industry Association, argues that robots actually save US jobs. His logic: companies that embrace automation might use fewer workers, but that’s still better than firing everyone and moving the work overseas.It’s not that robots are cheaper than humans, though often they are. It’s that they’re better. "In some cases the quality requirements are so exacting that even if you wanted to have a human do the job, you couldn’t." Burnstein says.Same goes for surgeons, who’re using robotic systems to perform an ever-growing list of operations- not because the machines save money but because, thanks to the greater precision of robots, the patients recover in less time and have fewer complications, says Dr. Myriam Curet.Surgeons may survive the robot invasion, but others at the hospital might not be so lucky. as iRobot, maker of the Roomba, a robot vacuum cleaner, has been showing off Ava, which could be used as a messenger in a hospital. And once you’re home, recovering, Ava could let you talk to your doctor, so there’s no need to send someone to your house. That "mobile telepresence" could be useful at the office. If you’re away on a trip, you can still attend a meeting. Just connect via videoconferencing software, so your face appears on Ava’s screen.Is any job safe I was hoping to say" journalist," but researchers are already developing software that can gather facts and write a news story. Which means that a few years from now, a robot could be writing this column. And who will read it Well, there might be a lot of us hanging around with lots of free time on our hands.What caused the greatest loss of jobs in America A. Using microprocessors extensively.B. Moving production to other countries.C. The bankruptcy of many companiesD. The invasion of migrant workers.