Because it possesses no permanent residents, which continent is excluded as a region in the textbook?

I haven't read said textbook but I would presume the answer would be Antarctica as it does not (to my knowledge) possess any permanent human residents.

Antarctica possesses no permanent residents and so is excluded as a region in textbooks. The climate of Antarctica is so cold that it fails to support a permanent population all the year round. The continent is bigger in size than Australia as well as Europe but is not counted as a region. Antarctica with its cold climate also does not support any type of vegetation and agriculture which in turn does not allow the people to survive and thrive.