The correct answer is option C. Single celled organisms and soft, bone less animals. The Precambrian ear was believed to be before evolution. Meaning more plants and complex animals. Therefore, organisms were single celled during that time.
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The answer to this question would be: hyoid bone
The hyoid bone is a bone with horseshoe shape that located below of the mandible. Hyoid bone is a bit special because it was not articulate/connect with other bones. Hyoid bone is used as the place for tongue muscle attachment, allowing the tongue to move more freely.
Answer:
b. hormones
Explanation:
"The endocrine system is made up of glands that make hormones. Hormones are the body's chemical messengers. They carry information and instructions from one set of cells to another"
