An administrator is trying to make a hard link to an ordinary file but ln returns an error. Which of the following could cause this?

The hidden status (indicated by a leading dot) of a file does not prevent the creation of a hard link.

A read-only source file does not prevent the creation of a hard link, as hard linking only creates a new directory entry pointing to the existing inode.

The type of file content, such as a shell script, has no bearing on whether a hard link can be created.

File ownership is not a strict requirement for creating a hard link, as long as the user has appropriate permissions (e.g., write permission in the target directory).

Hard links function by referencing the same inode number, which are unique only within a single filesystem. Therefore, a hard link cannot span across multiple distinct filesystems.