Which of these does NOT refer to a category in biological taxonomy?

As of current science, the categories in order of size, are life, domain, kingdom, phylum, class, order, family, genus and species. Kingdom was the biggest group in the days of Carl Linnaeus, who popularized this system, but broader classifications were added more recently.

Asked by Christina Loprieno · Last updated 5 years ago · 70.3K views · SOURCE