I think it is D.) all of the above
Answer:
Land vertebrates developed lungs, a new vein (the pulmonary vein) to take blood from them to the heart, and a double circulation, whereby the heart is effectively divided into two halves—one-half concerned with pumping incoming deoxygenated blood from the body to the lungs and the other with pumping oxygenated blood .
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Answer:
They are different layers that protect us...skin protects your muscles, and your muscles protect your cells
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answer: The atoms of different elements all have different numbers of protons. Meanwhile, the mass number of an atom consists of the total number of protons and neutrons it contains
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Answer:
find or determine what information you wanna collect
set a time for your data collection
determine you collection method
collect your data
lastly analyze your data
