Answer:
Oxygenated blood flows back to the heart through the pulmonary vein, back into your left atrium.
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Explanation:
The answer is D.
The basic metabolism depends on height, weight, age, sex and thyroid activity. Outside temperature and climatic conditions also influence significantly. Basal metabolism decreases with age from 2% to 3% per decade after adulthood. Children, on the other hand, have a basal metabolism that is twice as high as that of adults.
Unicellular means single cell organism
