The fertilisation is_____and development is______in sponges.

Options

A. External, indirect
B. External, direct
C. Internal, indirect
D. Internal, direct

Explanation

To answer the question "The fertilisation is_____ and development is______ in sponges," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Phylum**: Sponges belong to the phylum Porifera. Understanding this classification helps in knowing their reproductive and developmental characteristics.

2. **Fertilization in Sponges**: In sponges, fertilization occurs internally. This means that the sperm is released into the water and is taken into the body of the sponge, where it fertilizes the egg. This process is known as cross-fertilization.

3. **Development in Sponges**: The development of sponges is indirect. This means that after fertilization, the zygote develops into a larval stage before maturing into an adult sponge. The larval stage is free-swimming and eventually settles down to develop into the adult form.

4. **Fill in the Blanks**: Based on the information gathered:
- The fertilisation is **internal**.
- The development is **indirect**.

5. **Final Answer**: Therefore, the complete statement is: "The fertilisation is internal and development is indirect in sponges."