The earned value technique is a commonly u

问题：

The earned value technique is a commonly used method of performance measurement．It integrates project scop,schedule,and cost measures to help the project management team assess project performance.If aproject's Cost Performance Index(CPI=EV/AC) value less than 1.0，it means that______。

A．the cost savings for work completed
B．the project is ahead of its planned schedule
C．the cost overrun for work completed
D．less work was completed than was planned