Which Statement About Critical Chain Methodology Is Best

Which statement about critical chain methodology is best?

A) Activity durations estimated at a 50% level of successful completion are shorter than those estimated at a 90% level of successful completion.
B) Aggregated activity durations at a 90% level of successful completion are shorter than aggregated activity durations at a 50% level of successful completion.
C) The total safety buffer for aggregated activity durations is smaller than the sum of safety buffers for individual activity durations at any likelihood level estimate.
D) None of these statements is correct.