Running Chmod 640 Filea

Running chmod 640 filea.txt as a regular user doesn't update filea.txt' s permission. What might be a reason why chmod cannot modify the permissions?

A) filea.txt is owned by another user and a regular user cannot change the permissions of another user's file. filea.txt is owned by another user and a regular user cannot change the permissions of another user's file.
B) filea.txt is a symbolic link whose permissions are a fixed value which cannot be charged. is a symbolic link whose permissions are a fixed value which cannot be charged.
C) filea.txt has the sticky bit set and a regular user cannot remove this permission. has the sticky bit set and a regular user cannot remove this permission.
D) filea.txt is a hard link whose permissions are inherited from the target and cannot be set directly. is a hard link whose permissions are inherited from the target and cannot be set directly.
E) filea.txt has the SetUID bit set which imposes the restriction that only the root user can make changes to the file. has the SetUID bit set which imposes the restriction that only the root user can make changes to the file.