The answer is C- Excretory system. Hope this helps :)
I attached the image related to your concerned question.
In theory, the part of the brain that is responsible for the sleep wake cycle is the hypothalamus; specifically, the ventrolateral preoptic nucleus of the hypothalamus. In the image, the location of the hypothalamus is pointed by the green square.
<span>Protein</span>
<span>Cilia and flagella are made up of microtubules covered by
plasma membrane and they projection from the cell. Thus, cilia are flagella are
motile and designed to move substances over or around the cell and they can as
well move the cell itself. In eukaryotes, they are conserved in their polypeptide
composition, structure and function as motile and sensory organelles.</span>
I would say D...just because of the greenhouse effect