Which term refers to an internal skeleton?

Which term refers to an internal skeleton?

• A. Internal skeleton
• B. Spicules
• C. Plankton
• D. Nematocyst

Answer: (A)

The concept here is how animals are structurally supported from within. An internal skeleton is a framework built inside the body, made of bones or cartilage, that supports the body, protects organs, and serves as an attachment point for muscles. The term that matches this idea in the options is “internal skeleton,” which directly names that internal support system. This differs from an external skeleton, which would be on the outside, and from features like spicules (tiny skeletal elements in sponges), plankton (drifting organisms), or nematocysts (stinging cells). So the internal skeleton is the best descriptor for an internal framework.