namei
Reading the systemPackage: util-linux
Breaks a path down component by component, with each one's permissions. A "Permission denied" on a readable file comes from a parent directory without x, and this is the command that shows it.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
namei -l- Shows the permissions of every component of a path. This is what reveals the closed parent directory blocking access to an otherwise readable file.