Using which of the following control mode commands is the correct way to substitute all occurrences of /dev/ sdcwith /dev/sddwhile editing a file in vi?

A Linux administrator needs to remove a USB drive from a system. The unmountcommand fails, stating the device is busy. Which of the following commands will show the reason for this error?

A junior system administrator had trouble installing and running an Apache web server on a Linux server. You have been tasked with installing the Apache web server on the Linux server and resolving the issue that prevented the junior administrator from running Apache.
INSTRUCTIONS
Install Apache and start the service. Verify that the Apache service is running with the defaults.
Typing "help" in the terminal will show a list of relevant commands.
If at any time you would like to bring back the initial state of the simulation, please click the Reset All button.
CentOS Command Prompt

A Linux administrator must identify a user with high disk usage. The administrator runs the # du -s /home/
*command and gets the following output:

Based on the output, User3 has the largest amount of disk space used. To clean up the file space, the administrator needs to find out more information about the specific files that are using the most disk space.
Which of the following commands will accomplish this task?

Which of the following configuration files should be modified to disable Ctrl+Alt+Del in Linux?