Which of the following proverbs suits the gist of the story By heart best?

A．Look before your leap.

B．Speech is silver, but silence is golden.

C．He laughs best, who laughs last.

D．Don’t count your chickens before they are hatched.

买方主导型网络采购系统是采购人员开始网络采购而又不担风险的理想工具。