Final answer:
The given percentages of calcium, phosphorus, and oxygen correspond to the composition of bone, not human blood, soil, or a rock. Therefore, the correct option is a) .
Step-by-step explanation:
The question is asking for the identification of a substance based on the percentage composition of elements given: calcium 38.7%, phosphorus 19.9%, oxygen 41.2%.
These percentages are indicative of the composition of bone. Therefore, the correct option is a) Bone composition. Bones are primarily made up of a mineral called hydroxyapatite, which is composed mainly of calcium, phosphorus, and oxygen.
This substance provides the structural rigidity and strength to bones, enabling them to support the body and protect vital organs. The high percentage of calcium indicates the mineralized nature of bone tissue, which is essential for the maintenance of necessary body functions such as movement and calcium storage.
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