All adult insects have:

All adult insects are characterized by having three distinct body regions, which consist of the head, thorax, and abdomen. The head houses the sensory organs and mouthparts, the thorax is where the legs and wings (if present) are attached, and the abdomen contains the digestive and reproductive organs. Additionally, adult insects have six legs, which is a defining trait of the class Insecta. This anatomical structure sets insects apart from other arthropods that may have different numbers of legs or body segments. The combination of three body regions and six legs is a fundamental aspect of insect biology and classification, which reinforces why this answer is accurate.