Under which of the following conditions would a firm be most likely to issue variable-rate debt（）

A. Operating cash flows are positively correlated with short-term interest rates.

B. Operating cash flows are negatively correlated with short-term interest rates.

C. The yield curve is sloping sharply downward.

一个地区城市化发展到高级阶段时表现的特点有:

①城镇人口的比重增长缓慢甚至停滞　②城乡差别很小

③第三产业成为国民经济的主导产业　④非农业人口向农业人口转化

A．①②③

B．②③④

C．①③④

D．①②④