【正确答案】 C

【答案解析】[听力原文]
   The central parity rate of the renminbi, or the yuan, strengthened byll5 basis points to 6.8402 against the US dollar on Tuesday, according to the China Foreign Exchange Trade System. In China's spot foreign exchange market, the yuan is allowed to rise or fall by 2 percent from the central parity rate each trading day.
根据新闻可知，每个贸易日人民币可上下浮动2%。故选C。