What type of reference entry is the following source?

Teofelus, A. (2020). Current studies on online assessment . In H. H. Hamakali, S. Shilongo, & R. Muyunda (Eds.), Quality high education in twenty first century Namibia : Advances in theory and research (4th ed., pp. 115–129). Gamsberg Pty Ltd.


a.
Title of a book


b.
Newspaper article


c.
Chapter in a book


d.
Article in an academic journal