A technical support engineer receives a ticket from a user who is trying to create a 1KB file in the /tmp directory and is getting the following error: No space...

A technical support engineer receives a ticket from a user who is trying to create a 1KB file in the /tmp directory and is getting the following error: No space left on device. The support engineer checks the /tmp directory, and it has 20GB of free space.
Which of the following BEST describes a possible cause for this error?

A. The /tmp directory is not mounted. B. The filesystem is formatted with a 4MB block size. C. the filesystem ran out of inodes. D. The /tmp directory has been set with an immutable attribute.