The authors mean that you can't discriminate against someone because of the color of their skin or the problems they may have.
A. freshwater fishing.
my reasoning:
Inside the Middle East, most countries have large supplies of oil, (which helps make the countries rich as they are today because of oil demands), which takes out the options C & D. The Middle East, is located within the Sahara desert, and so can contribute to desert research (B) as well.
So A, is your most logical choice.
hope this helps
