Water entering a sponge chamber passes cells with collars and beating flagella that trap food particles. The best answer is:

Choanocytes, or collar cells, create water currents and capture suspended food particles in sponges. They are key to sponge feeding because Porifera lack a true digestive tract. This MCQ belongs to the Porifera topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.