Which of the following political issues in East Asia has raised the most security concerns?

The layers of earth are based on what two sets of characteristics?

Which of the following is the main purpose of using an anchored network of booms which funnel debris to a collection area?

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?