Explanation
A hard link is a directory entry that refers to the same inode as another file. An inode is a data structure that stores the metadata and the location of the data blocks of a file. A hard link allows multiple names to refer to the same file content, as long as they are on the same filesystem. Therefore, when a hard link is created, the inode reference count is increased by one, and when a hard link is deleted, the inode reference count is decreased by one. The file content is only removed from the disk when the inode reference count reaches zero, meaning that there are no more hard links to the file. In this scenario, after successfully creating a hard link called bar to the ordinary file foo, foo and bar both refer to the same inode and the same file content. The inode reference count is two. When foo is deleted from the filesystem, the inode reference count is decreased by one, but it is still one, meaning that there is still one hard link to the file. Therefore, foo would be removed while bar would remain accessible. The file content would not be removed from the disk until bar is also deleted. The other options are either incorrect or not applicable. The user is not prompted whether bar should be removed, too. The bar link would still exist and be usable, not unusable. 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)