In recent weeks, the speculators have been waging an all-out war on the american dollar. the strength of a nation's currency is based on the strength of that nation's economy — and the american economy is by far the strongest in the world. accordingly, i have directed the secretary of the treasury to take the action necessary to defend the dollar against the speculators. i have directed secretary connally to suspend temporarily the convertibility of the dollar into gold or other reserve assets, except in amounts and conditions determined to be in the interest of monetary stability and in the best interests of the united states. —richard nixon, august 15, 1971 which of the following statements describes a major cause of the policy shift outlined in the passage? a. the overvaluation of the u. s. dollar as a result of the bretton woods system b. the collapse of the american gold mining industry due to unsustainable mining practices c. the refusal of many european countries to exchange u. s. currency for gold d. the need to increase the supply of u. s. dollars to fund the arms race