Which order from least inclusive to most inclusive is correct?

• A. Species, genus, family, order, class, division
• B. Division, class, order, family, genus, species
• C. Division, order, class, species, genus, family
• D. Species, family, division, order, genus, class

Answer: (A)

In taxonomy, the levels are nested from narrow to broad: a species is the most specific unit, then groups of related species into a genus, those into a family, families into an order, orders into a class, and finally divisions (or phyla in zoology) into the broadest group. So the order from least inclusive to most inclusive is species, genus, family, order, class, division. This matches how organisms are grouped by shared characteristics at each level, with each step broadening the group.

Other sequences break this nesting. For example, starting with division places the broadest group first, which isn’t the least inclusive. Arranging species before genus or family in a way that places broader ranks ahead of narrower ones also violates the hierarchical flow. The correct sequence preserves the natural progression from the most specific to the most inclusive.