The correct option is
A Sponge
Choanocytes, also called as collar cells, are the specialised flagellated cells that form the inner layer of body wall of sponges. This inner layer is also called as choanoderm.
Collar cells are the characteristic feature of sponges. These cells help in nutrition, respiration, circulation, excretion and nutrition.
So, the correct answer is 'Sponge'.