Answer:
Serpentine minerals are made of tiny sheets of silica tetrahedrons that are loosely held together.
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.
Do you see the tectonic plates are moving away from each other
"A. cutting down most of the trees in a forest to make furniture" is the correct answer because some trees play a vital role in processing the carbon in the air.
