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The answer is terracing.
Terracing is a type of landscaping characteristic for steep slopes and mountains. Graduated terraces are used to farm on this kind of terrain to reduce erosion. This way crops are planted on graduated level areas and not on steep terrain, and risk of surface runoff is reduced.
The right answer is B.
The purpose of breathing is to do homeostasis, which means, to take CO2 out and get oxygen to our blood.
Babies live into the wound surrounded by liquid, so they don't need to breathe with their lungs.
All the things they needed to survive are taken from the mother thought the placenta.
The aortic valve separates the left ventricle from the aorta, while the pulmonary valve separates the right ventricle from the pulmonary artery. As the ventricles contract, ventricular pressure exceeds arterial pressure, the semilunar valves open and blood is pumped into the major arteries.