What best describes an internal skeleton?

What best describes an internal skeleton?

• A. A framework located outside the body made of chitin
• B. A supportive framework located inside the body, typically made of bone or cartilage
• C. A network of nerves
• D. An external shell for protection

Answer: (B)

An internal skeleton is a framework located inside the body that provides support, gives the body its shape, and acts as a lever system for movement. In animals with backbones, this endoskeleton is made mainly of bone and cartilage and grows with the organism, protecting internal organs while allowing muscles to move the body. This matches the description of something inside the body made of bone or cartilage.

In contrast, an external shell or exoskeleton lies outside the body, such as a chitinous coating seen in many insects and crustaceans. A network of nerves is not a skeletal structure at all, so it isn’t what an internal skeleton is.