Explanation
The file command determines the type of a file by using a definition database file which contains information about all common file types. The database file is usually located at /usr/share/misc/magic or /usr/share/file/magic and can be customized by the user. The file command analyzes the content and structure of the file and compares it with the patterns in the database file to identify the file type. The file command can also check the file name extension, but it does not rely on it. The other options are either invalid or do not perform the desired task.The magic, pmagic and hash commands are not valid Linux commands. The type command is used to display information about command type, not file type.
References:
* LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.3 Perform basic file management
* LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)