The skeleton of sponges is made up of___________?
Correct answer: C. Both of these
- A. Calcium
- B. Silica
- C. Both of these
- D. None of these
Explanation
Sponge skeletons may contain calcium carbonate spicules or silica spicules, depending on the group, and some also contain spongin fibres. Since both calcium and silica occur as skeletal materials, option c is correct. Students may choose a or b by remembering only one major sponge type instead of the diversity among sponge classes.
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