please answer the following multiple choice

Which one of the following statements is true regarding exchange rates in the flexible exchange rate system? Select one OA Exchange rates should always be at the long-run equilibrium which satisfies the purchasing power party OB Starting at the short-term equilibrium, if the market expects that country A's currency would appreciate in the future, then the demand for country's A currency would increase O c Exchange rates are only affected by short-run factors, e.g, speculating OD Interest rate arbitragers broaden the short-term dis-equilibrium Unsure