In which stage do insects possess a non-living protective layer?

The correct choice refers to the cuticle layer, which is an essential part of an insect's anatomy. The cuticle is a non-living, protective layer made primarily of chitin, which provides structural support and vital protection against environmental factors, predators, and desiccation. This layer forms the exoskeleton of the insect, allowing it to maintain its shape and protect its internal organs.

Insects at various developmental stages, including larval, pupal, and adult stages, all have a cuticle, but it is specifically the cuticle layer that is consistently described as non-living. During molting, which occurs in the larval and pupal stages, insects shed their old cuticle to allow for growth or transition to the next life stage. However, the cuticle itself remains non-living throughout these processes, serving as the protective barrier.