[&] The hexadecimal sequence "21 3C 61 72 63 68 3E 0A" indicates what type of file?
- Windows Update Binary Delta Compression File
- Rich Text Format
- Linux Deb File
- Telegram Desktop File

[&] What is a file signature?
- A hexadecimal sequence that identifies a file
- A secure certificate that identifies the file authenticity
- A hexadecimal sequence that identifies the author
- A sign off at the end of an email