According to this map the area that has the lowest elevation is B.
A close look at the map shows that the areas that are the lowest are the places were the green shade is darker and the area is from 0 to 150 ft.
What is a relief map?
This is a map that shows hills and valleys that are shaded rather than having these areas in contour lines.
Area B is the part that has Washington and Maryland.
Read more on relief maps on:
https://brainly.com/question/4296393?referrer=searchResults
