WDO Home Inspection Practice Exam 2025 – Comprehensive Prep Guide

The correct answer is the abdomen. Insects, classified under the class Insecta, are characterized by a distinct body structure that includes three primary regions: the head, thorax, and abdomen. The abdomen is the third segment and can typically be differentiated from those of other arthropods by its segmented structure and its role in housing vital systems, including the digestive and reproductive organs.

This segmentation in the abdomen allows insects to exhibit a variety of functions and adaptations, such as oviposition and digestion. In contrast, while other arthropods may have similar body segments, their configurations can differ significantly, which is part of what helps taxonomists distinguish different classes within the phylum Arthropoda. Elements like a tail, sub-thorax, or rear section do not represent distinct anatomical classifications that apply broadly across the insect class. Thus, the abdomen stands out as the defining third region in Insecta, setting them apart from other arthropods.