A proposal Intend to explain certainly facts or observation
Answer:
The answer is a.) Transform Boundary.
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.
The answer is letter d, it is because when a person becomes obese, he or she is likely to intake small amounts of food if he or she wants to maintain his or her weight and if the person does not want to gain weight anymore and than it is more different when gaining weight or when the person was in the point to become obese because he or she has ingested more food to gain weight.