关于保险合同的主体，下列说法错误的是( )。

A．关系人包括被保险人和受益人

B．当事人指投保人和保险人

C．保险主体可分为当事人和关系人两类

D．保险代理人、保险经纪人和保险公估人也是保险合同的主体

A team can accomplish much more than the sum of its individual members and yet frequently groups of people are seen to achieve less than () by the individual member working together.

A. could have been accomplished

B. must have been accomplished

C. should be accomplished

D. would be accomplished