Answer: from the pulmonary veins into the left atrium.
Explanation:
After oxygenation of blood in the lungs, the right and left pulmonary veins carry oxygenated blood and empties it into the left atrium. The left atrium then empties the blood into the left ventricle through the left atrioventricular valve.
With contraction, the ventricle pumps the blood to the systemic circulation through the aorta. The blood flow into the aorta is guarded by the aortic valve.
There are four main types of tissue: muscle, epithelial, connective and nervous. Each is made of specialized cells that are grouped together according to structure and function. Muscle is found throughout the body and even includes organs such as the heart. Our outer layer of skin is epithelial tissue.
The answer is mitochondrion, it is called as "the power of cell"
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<span>D: Viruses
I hope helped ^-^</span>
