How come an animal's carbon-14 levels do not start to decrease until it dies?
A)because it constantly replenishes its carbon-14 supply by eating plants with carbon-14 in them
B)because it constantly replenishes its carbon-14 supply by breathing air with carbon-14 in it
C)because it is constantly being bombarded with cosmic rays
D)carbon-14 only starts to decay after the animal dies
E)the carbon-14 levels do not decrease because the carbon-13 in its skin protects it from cosmic rays

Question

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An animal's carbon-14 levels do not start to decrease until it dies because it constantly replenishes its carbon-14 supply by eating plants with carbon-14 in them.

How Come an Animal's Carbon-14 Levels Do Not Start to Decrease