Which of these changes in the foodweb would cause a decrease in the population of tundra swans?

A. A decrease in the population of vegetation
B. An increase in the population of benthic invertebrates
C. An increase in the population of wading birds
D. A decrease in the population of osprey

The table below shows the elements that mainly comprise each of the four layers of earth: elements in layers layer main elements crust oxygen, silicon mantle iron, magnesium outer core iron, nickel inner core iron which of these elements make up the layer that is 0.2 to 1.1 percent of earth's total diameter?