As Susan stared at ______ piles of plastic in her recycling bin, ______ strong sense of responsibility made her stick to her recycling work.

A．不填；不填

B．不填; a

C．the ; a

D．the; the

价差的逆向运行、利率和汇率的变动等所产生的风险是套利交易的( )。

A．政策风险

B．市场风险

C．操作风险

D．资金风险