【正确答案】 A

【答案解析】[听力原文]
   The trading on China's stock market has been suspended for the second day this week after prices plunged by more than 7%. An automatic shutdown was triggered less than an hour after business opened, Steve Evens reports from Beijing. After the crash in Chinese share prices last year, the authorities tried to prop up prices. Fearing a further slump, they prevented large scale selling of shares by big Chinese institutions. They also instituted a rule that a 5% or more drop in prices will trigger a halt in trading. On Monday, official media said, it was a rare event. Now, though reoperated 3 days later, China has also spent about 20 billion dollars this week, trying to prop up prices and exchange rates.
   How much has China spent to prop up prices and exchange rates?
数字题。由画线句子可知，本周中国已经投入200亿美元，试图支撑价格和汇率。故答案为A。