Which of the following viruses automatically attaches itself to files when it infects a hard disk system?

Correct option is B

The correct answer is (b) File enclosure (envelop) virus
Explanation:
• A File Enclosure (or Envelope) virus is a type of file-infecting virus that wraps itself around an existing file.
• When the infected file is executed, the virus code runs first before passing control back to the original program.
• It "automatically attaches" to executable files (like .exe or .com) to ensure it spreads whenever the user runs software.
• This method allows the virus to remain hidden while piggybacking on legitimate system operations.
• These viruses typically target the hard disk system to ensure long-term residency and widespread infection of other files.
Information Booster:
• Malware is a broad term that includes viruses, worms, and trojans.
• Resident viruses stay in the RAM and infect files as they are opened or closed.
Additional Knowledge:
Polymorphic virus (Option a)
• This virus changes its own code or signature every time it replicates to avoid detection by antivirus software.
Overwrite virus (Option c)
• This virus deletes the data in the file it infects and replaces it with its own code, making the original file unusable.
Multipartite virus (Option d)
• This is a complex virus that can attack both the boot sector and the executable files simultaneously.