The correct answer is (a.) liver. The liver contains the tubules with sinusoids which is lined with macrophages that leads to the central venous structure. A liver is a vital organ that serves as a gland that plays an important role in animal's and vertebrae's metabolism.
I think the correct answer from the choices listed above is option A. It is the alveoli that is composed of single layer <span>surrounded by a network of capillaries. These are used to allow oxygen and carbon dioxide to move from the lungs to the bloodstream.</span>
This is more common sense rather than biology, but talking to someone would slow it down, so you know it’s not c or e. The best idea is b