Which of the Following Are the MAIN Reasons Why a Systems

Which of the following are the MAIN reasons why a systems administrator would install security patches in a staging environment before the patches are applied to the production server? (Select two.)

A) To prevent server availability issues
B) To verify the appropriate patch is being installed
C) To generate a new baseline hash after patching
D) To allow users to test functionality
E) To ensure users are trained on new functionality