Answering Questions – Around 100 words

I’m working on a Business question and need guidance to help me study.

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answer the question .

Questions that arise: Why does the dollar dominate trade even though alternate currencies are available (Euro, GBP, Yen and now Yuan(Renminbi). More so in swaps – when it should not really matter – Euro or GBP or Yen can be far more significant? What may explain it?