The correct option is C. Explanation of the Correct Answer (C) Statement C claims that the thorax of insects comprises three segments, only two of which bear a pair of appendages each. This statement is NOT true because, in insects, the thorax is indeed divided into three segments: the prothorax, mesothorax, and metathorax. However, all three segments of the thorax bear a pair of appendages, specifically legs.

• Prothorax: This segment has one pair of legs.
• Mesothorax: This segment has one pair of legs and typically bears the first pair of wings in winged insects.
• Metathorax: This segment has one pair of legs and usually bears the second pair of wings in winged insects.

Thus, all three segments of the thorax have a pair of appendages, making statement C incorrect. Explanation of Why Other Options Are Correct Option A: They are arthropods. - This statement is true. Insects belong to the phylum Arthropoda, which is characterized by having an exoskeleton, segmented bodies, and jointed appendages. Other members of this phylum include arachnids (like spiders) and crustaceans (like crabs). Option B: Their body is divided into three distinct regions of head, thorax, and abdomen. - This statement is also true. Insects have a body plan that is divided into three main parts: the head (which contains sensory organs and mouthparts), the thorax (which is responsible for locomotion and bears the legs and wings), and the abdomen (which contains the digestive and reproductive organs). Option D: Respiration is by means of trachea. - This statement is true as well. Insects breathe through a system of tubes called tracheae, which deliver oxygen directly to their tissues. The tracheal system opens to the outside through small openings called spiracles, allowing for efficient gas exchange. Summary of Key Points

• Insects have three thoracic segments, and all bear a pair of legs, making option C incorrect.
• Insects are classified as arthropods, which is a true statement (option A).
• Their body is divided into three regions: head, thorax, and abdomen (option B).
• Insects respire through a tracheal system, which is an accurate description (option D).

Revision Summary

• Insects are arthropods with a segmented body plan.
• The thorax has three segments, each with a pair of legs.
• Insects have a head, thorax, and abdomen.
• They breathe through a tracheal system, not through gills or lungs.