Amap with a scale of 1: 24,000 means that blank . a. one unit on the map is equal to 24,000 units on the ground b. one unit on the ground is equal is 24,000 units in the map c. the contour interval is 24,000 feet d. the contour interval changes every 24,000 feet

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?