Difference between plough and tractor

What's erosion? a. the breakdown of rock into smaller pieces b. the removal of weathered products from rock c. a change in rock resulting from exposure to water d. a chemical change in rock that weakens it

Can someone answer all these questions i need it done by tonight. once again

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?