According to Olney what is necessary to prevent a nation from deteriorating?

could you send me the choices?

answer; andrew jackson approved nullification by signing it into law,and john calhoun opposed it saying it was unconstitutional;

the causes of the dust bowls were severe droughts,   lands became dry and hard, temperature was higher than usual, hot and dry conditions killed crops, high winds. because of those factors, the winds kicked up dry soil and created clouds of dust.

international economic development agencies harm poorer nations by encouraging them to serve as exporters to wealthier nations.