Why did the elevation of land is measured from the level of sea?

Which quotation reflects the perspective of most of georgia legislatures in 1956 regarding the georgia state flag? question 4 options: "georgia's flag should be updated to have a more modern look and design." "georgia's flag should be a symbol of integration and equal rights." "georgia's flag does not need to be changed; it represents peace and prosperity." "georgia's flag should be a symbol of our resistance to federal integration laws."