It is done to provide for better engine performance. It is important for two main reasons. One is that if one ignition system fails the other can for a time take care of it and hold its ground until you land or fix it. Another is that it is used for more efficient consumption of fuel and air which makes the engine work better.
I would have to say it would be A. log file.
Answer:
I think A modern operating system is usually used in personal computers
Oh my- good luck with that-