Which of the following is correct ?

Options

A. All fungi are filamentous.
B. Transfer of DNA cannot take place from one bacteria to another.
C. A virus cannot have both DNA and RNA .
D. Protists can reproduces only asexually.

Answer

To solve the question of which statement is correct, we will analyze each of the four statements provided:

1. **Statement 1: All fungi are filamentous.**
- Fungi are primarily known for their filamentous structures called hyphae. However, not all fungi exhibit this characteristic. For instance, yeasts are a type of fungi that do not have a filamentous structure; they exist as single-celled organisms. Therefore, this statement is **incorrect**.

2. **Statement 2: Transfer of DNA cannot take place from one bacteria to another.**
- Bacteria can exchange genetic material through various processes, including conjugation, transformation, and transduction. This means that DNA transfer between bacteria is indeed possible. Thus, this statement is also **incorrect**.

3. **Statement 3: A virus cannot have both DNA and RNA.**
- Viruses can contain either DNA or RNA as their genetic material, but not both simultaneously. A virus is composed of a protein coat (capsid) that encases its genetic material. Therefore, this statement is **correct**.

4. **Statement 4: A protist can reproduce only asexually.**
- Protists are a diverse group of organisms that can reproduce both asexually and sexually. They can undergo sexual reproduction involving processes such as self-fusion and zygote formation. Hence, this statement is **incorrect**.

Based on the analysis, the only correct statement is **Statement 3: A virus cannot have both DNA and RNA**.

### Final Answer:
The correct statement is **Statement 3**.