The causes of variances and the reasoning behind the corrective action chosen are summarized the ______ .

A) work breakdown structure
B) accounting codes for the activities
C) lessons learned
D) performance reports

下面选项中不属于数据库安全模型的是：（）

A.自主型安全模型

B.强制型安全模型

C.基于角色的模型

D.访问控制矩阵