Answer:
<u>O Animal bones</u>
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Explanation:
In the upper atmosphere, Radioactive Carbon-14 is usually produced. In plants, it is incorporated by photosynthesis into organic molecules, later ingested by hetrotrophs.
It is used for the radiocarbon dating process of fossils and formations. Because of the unstable nature of the isotope used and the consistent rate of decay, radioactive isotope dating is an important way of detection in organic material. Here, this is a the measure of the time taken for half of the radioactive material to break down- this is called the half life for Carbon this is 5,730 years.
In animals, the Carbon-14 ingested is eventually incoporated into their bones. After they die, bones become dessicated, and the Carbon 14 is slowly broken down to become Nitrogen.
