The correct answer is option 2: Chromatophore. Chromatophores are specialized cells found in the skin of certain animals, including chameleons, that contain pigments responsible for their coloration. These pigments can be transferred to different parts of the cell, allowing the chameleon to change its color. When the pigments are close together, they absorb most of the light and the chameleon appears darker. When the pigments are spread apart, they reflect more light and the chameleon appears lighter. This ability to change color is controlled by the chameleon`s neurological system in response to various stimuli, such as temperature, light, or mood. Haemoglobin is a protein in red blood cells that carries oxygen, while chlorophyll is a pigment found in plants involved in photosynthesis. Pneumatophore is a specialized root structure in certain plants.