First, just simply do the usual for the letter as always, then introduce the three topics you're talking about and like it said: describe it or basically define it, list 3 facts, and your opinion.
Answer:
It would prevent the concentration of power.
Option b. full employment
Full employment as an employment rate that includes no cyclical (also known as deficient demand or Keynesian) unemployment in other words, when there is enough overall demand in the economy for everyone who wants a job to have one.