【单选题】

In your construction project, theCPI is 1.30 and SPI is 0.85. What could be the potential reason

A、A、critical resource went on sick leave for a long period of time, which had not been anticipated earlier.
B、TheCost of raw materials required for construction increased 10%.
C、You had not taken into account inflation rate.
D、There was 4 days waiting time in the curing of cement, and work could not be done during that time.