单选题 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

【正确答案】 B

【答案解析】[分析] 细节题型。根据第二段第二句的...his job is made more difficult by retail demand not necessarily running level with manufacturers' production. run level with同等的。