What's the T C O(編號:792)

請看MCSD考題
Which is not a goal of the TCO manage phase ?
A.Monitor , track and adjust affected projects.
B.Establish an improvement cycle.
C.Re-establish the baseline.
D.Create What-if scenarios to simulate the costs and benefits of improvement projects.
Answer is : D
所以請問 TCO 是什麼的縮寫 ?