What is the best approach to achieve the goal?

A shared client computer running Windows 7 is responding and loading applications slowly.
Windows Task Manager indicates that available memory is low and that several applications, which
are not running on the desktop, are using a large amount of memory. You need to recommend an
approach for optimizing the performance of the client computer. What is the best approach to
achieve the goal? (More than one answer choice may achieve the goal. Select the BEST answer.)

A.
Use Task Manager to end unknown processes and processes that are not associated with the
currently active user account

B.
Log off all users other than the currently active user from the client computer

C.
Restart Windows Explorer

D.
In the Services Management console, stop unnecessary services

Explanation:
http://www.optimizingpc.com/windows7/optimizing_windows_7_services.html