C. increased job opportunities :)
I think that a) is chemical, and b) would be chemical
Consisting of Lakes<span> Superior, Michigan, Huron (or Michigan–Huron), Erie, and Ontario, they form the </span>largest group of freshwater lakes<span> on </span>Earth<span>, containing 21% of the </span>world's<span> surface </span>fresh water<span> by volume.
Hope This Helps!</span>
Can you give a closer picture?
This Should Help a Little:
A largely semi-arid belt of barren, sandy and rock-strewn land, the Sahel marks the physical and cultural transition between the continent's more fertile tropical regions to the south and its desert in the north. ... The Sahel also suffers from ethno-religious tensions, political instability, poverty and natural disasters.
