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
