Which of the Following Statements Is Most Correct

Which of the following statements is most correct?

A) Exporters may use sight or time drafts in billing foreign customers when they have confidence in the purchaser's ability and willingness to pay.
B) A time draft becomes a banker's acceptance when the customer receives, signs, and returns the draft to the exporter.
C) The currency rate is the rate at which a given unit of a foreign currency is quoted in terms of gold.
D) All of the above statements are correct.