下列货币政策工具中，属于直接信用控制的是（）。

A.道义劝告

B.贷款限额

C.利率限制

D.流动性比率

E.窗口指导

A middleman's work may become difficult because ______.

A．manufacturers run their production on a much higher level

B．market demand may not be the same as industrial production

C．retailers are not necessary in running their retailing business

D．retailers demand lower levels than those demanded by manufacturers