单项选择题
Whichitemisthemostimportantfactorduringdeploymentofhigh－availabilityfeatures？（）
A.Testmajorchangesbeforedeploymentanddeferminorchangesuntilduringdeployment.
B.Documentandverifyrollbackprocedures.
C.Ensureconsistencyofcodeversionsacrossthenetwork.
D.Progressivelymodifyproceduresanddocumentationduringimplementation.