Which of the following is NOT a domain in the classification system?

The correct answer is that "Eukaryotic" is not a domain in the classification system. The classification system of life is divided into three main domains: Archaea, Bacteria, and Eukarya (not "Eukbacteria" as listed in one of the options). The term "Eukaryotic" refers to an organism that possesses a complex cell or cells with a nucleus, typically associated with the domain Eukarya, but it is not itself a defined taxonomic category or domain.

In contrast, Animalia is a kingdom within the domain Eukarya, Archaea is one of the three primary domains of life, and the term "Eukbacteria" seems to be a confusion or a misnomer as there is no domain by that exact name; it likely intends to refer to the domain Bacteria. Therefore, "Eukaryotic" does not fit into the classification at the domain level, making it the correct response to the question.