Utility function is a commonly used technique to find out the tolerance of a project manager towards risk．Some project managers are more averse towards risk than others．All the following are different classifications of tolerance for risk EXCEPT______．

A．Project file
B．Commercial database
C．Project team knowledg
D．Lessons learned database

A．inform the public that a detailed examination has been ordered to determine the extent to which the problem exists
B．do nothing because there is extremely low risk for sickness except for some effects on small children and the elderly
C．tell the public there is no problem，except for small children and the elderly who need to boil the water before drinking
D．educate the public about the advances on water treatment technology and the industry efficiency and safety record