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