A checksum is a cryptographic hash function (like MD5 or SHA-256) used to verify the integrity of files. When downloading files from the internet, websites often provide the checksum value of the file so that users can ensure the file was not altered during download or corrupted. The user can generate the checksum on their local system and compare it to the one provided by the site. If they match, the file is intact and safe to use. Other options like BitLocker or FileVault are encryption tools, and a password manager is irrelevant to file verification.
Reference:
CompTIA A+ 220-1102 Domain 3.5: File Integrity Checking (CompTIA) (ProfMesser)

EAP-TLS is a method of authentication that uses certificates to establish a secure tunnel between the client and the server3. The certificates have a validity period and must be renewed before they expire1. If the user has been on an extended leave and has not logged in to the computer in several months, it is possible that the certificate on the client or the server has expired and needs to be renewed2. The other options are not directly related to EAP-TLS authentication or 802.1X network access.

For rendering video, the most critical component a customer should prioritize in a desktop is:
* GPU (Graphics Processing Unit):The GPU is specifically designed to handle complex graphics and video rendering tasks. A powerful GPU will significantly improve performance in video rendering applications.
* NIC (Network Interface Card):Important for network connectivity but irrelevant for video rendering.
* USB:Useful for peripherals but does not impact video rendering capabilities.
* HDMI:An important output interface for connecting monitors but not crucial for the rendering process itself.
Reference:
CompTIA A+ 220-1102 Exam Objectives, Section 1.8: Explain common OS types and their purposes, including hardware components for specific tasks.
GPU importance in video rendering documentation.

If a rootkit has caused a deep infection, then the only way to remove the rootkit is to reinstall the operating system. This is because rootkits are designed to be difficult to detect and remove, and they can hide in the operating system's kernel, making it difficult to remove them without reinstalling the operating system
https://www.minitool.com/backup-tips/how-to-get-rid-of-rootkit-windows-10.html