Task A has a cost estimate of US$1,000 and a scheduled completing date of December 30, with a total duration of 10 days, The project manager reviews the project if task on December 30 and it is only 70% complete. The resource assigned to task A has spent US$600 to date.What is the planned value?
A、US$400
B、US$600
C、US$700
D、US$1,000