The same question has been raised by others on LnkedIn, etc and received the following reply from Martin Thomas a consultant
"you did this before and didn't get much in the way of answer because this is not hte place to get people to do your homework for you."
Please search the web using key words from your query and you may find some explantions.
Have a nice day
You didn't even change the question. It's straight out of a schoolbook.