Little is known inside or outside North Korea about the young man _____could become the next leader. [ ]

A. who

B. which

C. whom

D. /

排他交易的好处包括（）。

A.加强对分销商的控制

B.便于生产商对销售的管理

C.增加渠道的弹性

D.减少整个流通体系的费用