A chameleon's ability to change the colour of its skin to match its surroundings is a well-known example of camouflage, which is a form of defensive adaptation. By blending into the background, the chameleon becomes difficult for predators such as birds and snakes to detect. This dramatically increases its chances of survival.
The colour change is achieved through specialised pigment-containing cells called chromatophores in the skin. Different layers of chromatophores contain different pigments, and the chameleon can expand or contract these cells to produce a wide range of colours and patterns that match the surrounding vegetation, bark, or soil.
While colour change in some contexts can play a role in communication or thermoregulation, the primary biological advantage tested at this level is defence against predation. The other options do not accurately describe the main survival purpose of this adaptation: it is not primarily for attracting mates, inviting other organisms, or launching attacks on prey.
Exam tip: Camouflage, mimicry, and warning colouration are all classified as defensive adaptations. When a question asks about an organism blending with its environment, the answer points to protection from predators.