The right answer is vein (it contains blood and has valves).
The infra-cardiac veins of small and medium caliber possess this system of fight against gravity. The valves consist of a dense connective tissue, surmounted by endothelial cells, corresponding to a fold of the intima. They allow blood circulation in the sense organ / heart but prevent venous reflux.
It has something to do with finding the aftershocks of 3 locations around it.
Answer: I think B . Like the second one
Explanation:
it is because of they raise the animals then we will have more food . Milk and help from the animals .
The epiglottis. It prevents food from entering the respiratory tract
