There have been many different forces that have linked Arab nations, but most of these links have come from military dominance in one way or another.
A demilitarized zone is a zone where weapons and military aren't allowed
The Southerners opposed industry because their main revenue came from exported crash crops grown in plantations. The Southerners saw no need to incorporate industry since they thought it would not be useful at all.
I believe the answer is,
The life expectancy of the average worker.
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