When a viral DNA is incorporated inside the host DNA,it is known as :

Options

A. Phycophages
B. Cyanophages
C. prophage
D. Vegphage

Answer

To solve the question "When a viral DNA is incorporated inside the host DNA, it is known as:", we will analyze the options provided and identify the correct term based on biological concepts.

### Step-by-Step Solution:

1. **Understanding the Question**: The question is asking for the term used when viral DNA integrates into the host DNA. This is a common process in virology, particularly with certain types of viruses.

2. **Analyzing the Options**:
- **Phycophages**: These are viruses that infect algae. This option is not relevant to the incorporation of viral DNA into host DNA.
- **Cyanophages**: These are viruses that infect cyanobacteria. Again, this option does not relate to the incorporation of viral DNA into host DNA.
- **Prophages**: This term refers to the stage when a bacteriophage (a virus that infects bacteria) integrates its DNA into the bacterial host's genome. This is the correct term we are looking for.
- **Phages**: This is a general term for viruses that infect bacteria, but it does not specifically refer to the incorporation of viral DNA into host DNA.

3. **Identifying the Correct Answer**: Based on the definitions and the context provided, the correct answer is **Prophages**. This term specifically describes the state of a bacteriophage when its DNA has been integrated into the host DNA without causing lytic activity or infection.

4. **Conclusion**: Therefore, when a viral DNA is incorporated inside the host DNA, it is known as **Prophages**.

### Final Answer:
**Prophages**