单项选择题The earned value technique is a commonly used method of performance measurement. It integrates project scope, cost, and schedule measures to help the project management team assess project performance. If a project’s Schedule Performance Index (SPI=EV PV) value less than 1.0, it means that ______.
A. the project is ahead of its planned schedule
B. less work was completed than was planned
C. the cost overrun for work completed
D. the cost under-run of performance to date