What is true about the owner of a file?

What is true about the owner of a file?
A . Each file is owned by exactly one user and one group.
B . The owner of a file always has full permissions when accessing the file.
C . The user owning a file must be a member of the file’s group.
D . When a user is deleted, all files owned by the user disappear.
E . The owner of a file cannot be changed once it is assigned to an owner.

Answer: A