Do you think walls are effective at separating nations?

No

Explanation:

I don't believe a physical barrier is needed to know where a country ends and starts. 1. all it causes is tension, it makes people think something is wrong with the other side, like aliens. 2. Think about what the Berlin Wall did, people cheated around it anyways. It also only caused death and destruction. 3. signs can be very pretty ways of welcoming people :)

answer; i believe that the correct answer is (c) arctic tundra;

c) troops march forward in close formation against newer, more accurate weapons