1-3 are the same thing. The US held most of the world's assets (was a creditor during the war), so became the world's most well capitalized bank. In that capaci

1-3 are the same thing. The US held most of the world's assets (was a creditor during the war), so became the world's most well capitalized bank. In that capacity, the bank's notes, i.e. dollars, became the world's currency. Despite a run on the "bank" in the 70's, this arrangement remained.