How does the skeletal system of an embryo differ from that of an adult?

a.) almost the entire system of an embryo is made of cartilage, whereas that of an adult is mostly made of bones.
b.) almost the entire system of an embryo is made of bones, whereas that of an adult is mostly made of cartilage.
c.) almost the entire system of an embryo is made of bones, whereas that of an adult is made of bones and cartilage in equal proportions.

Almost the entire system of an embryo is made of cartilage, whereas that of an adult is mostly made of bones.

An embryo is a multicellular diploid eukaryote in an early stage of embryogenesis, or development. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell.

Biologically, an adult is a human being or other organism that has reached sexual maturity.

The correct answer between all the choices given is the first choice or letter A. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.