After an administrator successfully migrated the last physical application server to a virtual environment, the help desk reported slow performance. Which of the following should the administrator have done FIRST before migrating this server?
A. Apply operating system patches to the application server after the migration.
B. Contact the vendor to see if the application is supported in a virtual environment.
C. Take a backup of the application server after the migration.
D. Migrate the application server in a test environment and have users test it.