A learner makes a note: a large sponge has many flagellated chambers and a highly folded canal system that increases feeding surface area. The missing scientific idea is:

Correct Answer: A

leuconoid canal system

The leuconoid canal system is the most complex sponge water-current system. It contains many flagellated chambers and supports larger sponge body size by increasing filtration efficiency. This MCQ belongs to the Porifera topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.