You have a computer that runs Windows XP Professional. Five users share the computer. A user named User1 is a member of the Power Users group and the Administrators group. User1 has encrypted files on the computer. User1 takes an extended leave of absence. You need to ensure that users cannot access the computer as User1. You must be able to provide User1 access to the files upon User1’s return. What should you do?（）

A. Disable the User1 account.
B. Add User1 to the Guests group.
C. Reset the password for the User1 account.
D. Rename ntuser.dat as ntuser.man in the User1 user profile.