Policy that favored people born in the in the united states during the early 1800's was called

Why was it decided in potsdam that certain industries in germany would be disabled? a. to deplete resources that might prevent germany from coming to power again b. so that a portion of the eastern region of poland would be fused together with the soviet union c. to allow the allies to focus their war efforts in fighting the last part of the war against japan d. to provide economic aid for iran's government since large war demands were made on them