Which of the following is correct?

Options

A. all fungi are filamentous
B. transfer of DNA from one bacteria to another bacteria cannot take place
C. virus cannot have both DNA and RNA
D. protists reproduce asexually only

Explanation

To solve the question, we need to evaluate each of the provided statements to determine which one is correct. Let's analyze them step by step:

### Step 1: Analyze the first option
**Statement:** All fungi are filamentous.
**Analysis:** This statement is incorrect. While many fungi do have a filamentous structure known as hyphae, not all fungi are filamentous. For example, yeasts are unicellular fungi that do not form hyphae.
**Conclusion:** This option is incorrect.

### Step 2: Analyze the second option
**Statement:** Transfer of DNA from one bacteria to another bacteria cannot take place.
**Analysis:** This statement is also incorrect. Bacteria can transfer DNA through several mechanisms: transformation (uptake of free DNA), transduction (transfer via bacteriophages), and conjugation (transfer through direct contact).
**Conclusion:** This option is incorrect.

### Step 3: Analyze the third option
**Statement:** Virus cannot have both DNA and RNA.
**Analysis:** This statement is correct. Viruses can have either DNA or RNA as their genetic material, but not both simultaneously. They are classified based on the type of nucleic acid they contain.
**Conclusion:** This option is correct.

### Step 4: Analyze the fourth option
**Statement:** Protists reproduce asexually only.
**Analysis:** This statement is incorrect. Protists can reproduce both asexually (through methods like binary fission) and sexually (through processes like conjugation or gamete formation).
**Conclusion:** This option is incorrect.

### Final Conclusion
After analyzing all the options, the correct statement is: **"Virus cannot have both DNA and RNA."**

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