1. Area A: 1,401-1,700
Area B: 1,001-1,200
Area C: 2,201-38,000
Area D: 0-800
Area E: 0-800
2. They can use it to decide where the best place to build a school in proportional to the population be, or make more convenient bus stops, etc.
3. I would choose C since I believe that's the best option for the most obvious reason: population. More people in an area means more business there. Besides, it's also roughly the same distance away to both A, B, and D.
4. I would probably put it in B or E. This is a warehouse distribution center by a large corporation, so in that case B and E are better options than A, C, or D. Nevertheless, E is closer to the two highways (which can directly lead me to B and D) and E is right at the airport which is really convenient.
:)