Technician a says that to prevent the machine from starting by accident when you're working on it, disconnect the ignition system before starting work. technician b says that one of the most important parts of any safety-and-accident-prevention program is good housekeeping. who is correct?

Both Technician A and Technician B are correct. 
When working on an ignition system, it is important to make sure it is turned off, because any spark or incidental flow of energy could result in a serious accident. 
Technician B is correct that good house-keeping is essential to accident prevention. Keeping the work area neat, clean, and free of debris and other substances goes a long way in preventing an accident. A messy, dirty work area prevents many obstacles and hazards and can result in injury or worse. 

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