Nervous system in sponges is

Options

A. primitive
B. well developed
C. without a definite brain nerves
D. absent

Answer

### Step-by-Step Solution:

1. **Understanding Sponges**: Sponges belong to the phylum Porifera, which are simple multicellular organisms. They have a porous body structure that allows water to flow through them.

2. **Structure of Sponges**: The body of a sponge is organized around a system of canals and chambers. The outer layer consists of specialized cells called pinacocytes, while the inner layer is lined with choanocytes (or collar cells) that help in filtering food from the water.

3. **Nervous System in Sponges**: Unlike more complex animals, sponges do not have a centralized nervous system. They lack nerve cells or tissues that are typically found in higher organisms.

4. **Function of Choanocytes**: The choanocytes play a crucial role in the sponge's feeding and water flow. They create a current that draws water into the sponge through small openings called ostia and expels it through a larger opening called the osculum.

5. **Absence of Nervous System**: Due to their simple structure and lifestyle, sponges do not require a nervous system. They do not have specialized organs for processing information or responding to stimuli in the way that more complex animals do.

6. **Conclusion**: Therefore, it can be concluded that sponges do not possess a nervous system, which is a characteristic feature of their primitive organization.