Which command is used to determine the type of a file using a database of common file types?

The command that determines the type of a file using a database of common file types is "file." This command analyzes the content of a specified file and compares it against a predefined database of file signatures to ascertain the file type. For example, when you run the file command followed by a filename, it inspects the file's content and provides output that indicates whether it's a text file, executable, image, or another type. This capability is especially useful for identifying files quickly without having to check their extensions, which can sometimes be misleading.

In contrast, other choices do not serve the same purpose. The type command is generally used to determine how a command would be interpreted in the shell, while ls lists directory contents. The stat command provides detailed information about the file's status (like size and modification time) rather than identifying its type.