Most likely to be A which is probably an artery which carries blood away from the heart Nd tens to carry oxygen rich blood
the leg doesnt contain aveoli this is found in the lungs so its not B
since its oxygen rich little carbon dioxide will be present in this structure so its not C
this part cant be part of the respiratory system as the respiratory system includes lungs, mouth and etc but not the legs so it cant be D
hope that helps
Bacteria in our gut help to protect us by crowding out some of their dangerous relatives that can cause disease. Other good bacteria have been used in medicine to create antibiotics, and others still are used in food production to make fermented foods (think sauerkraut, yogurt, kimchi and kombucha.)

Cellular homeostasis involves maintaining a balance of several factors that make a cell healthy. The cell membrane is a lipid bilayer that prevents that passage of water and ions. This allows cells to maintain a higher concentration of sodium ions out the outside of the cell.
<span>Geographically isolated populations may live under different environmental conditions, which can lead to each of these separated populations adapting differently to these different conditions. Given enough time, these little changes can lead to those populations diverging into distinct species after so many successive generations. </span>
