To locate a missing file with only a partial name known, the best tools to use in a Linux environment would be grepandfind.
grep:This command is used to search the contents of files for a specific pattern. Whilegrepitself might not be the first choice for finding file names, it can be combined with other commands (likelsorfind) to search within file lists or contents.
find:This command is used to search for files in a directory hierarchy based on various criteria like name, size, modification date, etc.findcan be used to search for files by partial name by using wildcards in the search pattern.
cat(A) is used to concatenate and display the content of files.df(B) displays the amount of disk space used and available on filesystems.ps(D) shows information about active processes.dig(E) is used for querying DNS name servers.top(G) displays Linux tasks and system performance information. None of these tools are directly suited for finding files by partial names.

Comprehensive and Detailed In-Depth Explanation:
The two best first steps are:
* Perform a virus scan - Multiple users on a device increase the risk of malware, which can cause performance issues.
* Check the startup programs - Unnecessary programs running at startup can slow down the system.
* C. Back up the data - Important but not the first step for performance troubleshooting.
* D. Disable the guest account - May prevent future unauthorized use but does not immediately fix the current issue.
* E. Update the firmware - Firmware updates improve hardware stability but are unlikely to fix a sudden performance drop.
* F. Reinstall the operating system - A last resort, as it erases data and takes significant time.
Reference:
CompTIA A+ 220-1102, Objective 2.4 - Malware and Security Threat Removal

AUP (Acceptable Use Policy) should be updated to reflect this new requirement. The AUP is a document that outlines the acceptable use of technology within an organization. It is a set of rules that employees must follow when using company resources. The AUP should be updated to include a policy on cryptocurrency mining on work desktops

According to CompTIA A+ Core 2 objectives, a full backup stored off-site provides the greatest protection against data loss in the event of a ransomware attack or other data disaster. By storing the backup in a separate physical location, it is less likely to be affected by the same event that could cause data loss on the original system. Cold storage is a term used for data archiving, which typically refers to a long-term storage solution that is used for retaining data that is infrequently accessed, but still needs to be kept for regulatory or compliance reasons.

Rebooting the computer into safe mode (Option B) limits the processes and services that run, which can help in isolating and removing persistent malware that might be hiding in normal mode. Safe mode provides a cleaner environment to troubleshoot and remove malware.
* Restoring from a backup (Option A) may work but should be considered after attempts to clean the infection.
* Purchasing a new endpoint protection tool (Option C) is unnecessary at this stage since existing tools can be run in safe mode.
* Using system recovery (Option D) could potentially remove the infection, but it's a more drastic step that may not be necessary yet.
CompTIA A+ Core 2 References:
* 3.3 - Best practices for malware removal, including booting into safe mode