31 Refer to the Following Diagram, in Which Waa/Ww Is

31 refer to the following diagram, in which Waa/Ww is the ratio of the African American wage rate to the white wage rate:
-The demand curve in the diagram eventually slopes downward because:

A) as the African American-white wage ratio falls,more firms find it "too costly" to indulge their tastes for discrimination
B) as the African American-white wage ratio rises,more firms find it "too costly" to indulge their tastes for discrimination
C) as the African American-white wage ratio falls,firms will raise their discrimination coefficients
D) as the African American-white wage ratio falls,firms will reduce their discrimination coefficients