The earned value technique is a commonly used method of performance measurement. It integrates project scope, schedule, and cost measures to help the project management team assess project performance. If a project'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