Final answer:
The correct answer is Ascon. Sponges with the ascon body plan have a cylindrical shape with a central cavity called the spongocoel and numerous pores in the body wall.
Step-by-step explanation:
The correct answer is Ascon. Sponges exhibit a range of diversity in body forms, but the simplest sponges have a body plan known as 'ascon.' The ascon body plan is a cylindrical shape with a large central cavity, the spongocoel, and numerous pores in the body wall that allow water to enter. Water flows out through a large opening called the osculum.