Which of the following is the MOST likely cause of this issue?

Joe, a customer, calls a technician to report a remote computer is demonstrating erratic behavior while he is working on it. The technician verifies the files and directories. Joe is working on locally cannot be opened in any application, and the computer is running extremely slow.

Which of the following is the MOST likely cause of this issue?
A . Files disappearing
B . File permission changes
C . Application crash
D . Too many startup items

Answer: D