15. which excretory organ eliminates water and some chemical wastes in perspiration?

I think the answer is skin. Skin contains sweat glands which secrete a fluid waste called sweat or perspiration; nonetheless, its primary functions are temperature control and release of pheromone. Its role as a part of the excretory is therefore minimal. Additionally, sweating also maintains the levels of salt in the body.

Region b indicates the occipital lobe

Very hard to understand