【单选题】

The "rolling wave" or "moving window" concept is used most frequently on projects where: 

A The baseline is frozen for the duration of the project and no scope changes are permitted 
B Marketing is unsure of what the customer actually wants and reserves the right to make major scope changes 
C The low levels of the work breakdown structure are known with certainty for the next three to six months, but the remaining tasks are based upon the results of the first three to six months of work 
D Networking techniques are not appropriate 
E All of the above