Which of the following is effective against virus?

Options

A. Penicillin
B. Interferon
C. Tetracycline
D. All of these

Answer

To solve the question "Which of the following is effective against viruses?" we will analyze each option provided.

### Step-by-step Solution:

1. **Identify the Options**: The options given are:
- A) Penicillin
- B) Interferons
- C) Tetracycline
- D) All of these

2. **Evaluate Option A: Penicillin**:
- Penicillin is a type of antibiotic derived from Penicillium molds.
- It is specifically effective against bacteria, not viruses.
- Therefore, Penicillin is **not effective against viruses**.

3. **Evaluate Option B: Interferons**:
- Interferons are a group of signaling proteins (cytokines) released by host cells in response to viral infections.
- They have antiviral properties and help to inhibit viral replication.
- Therefore, Interferons **are effective against viruses**.

4. **Evaluate Option C: Tetracycline**:
- Tetracycline is another type of antibiotic, derived from Streptomyces rimosus.
- Like Penicillin, it is effective against bacteria and does not have any effect on viruses.
- Therefore, Tetracycline is **not effective against viruses**.

5. **Evaluate Option D: All of these**:
- Since both Penicillin and Tetracycline are not effective against viruses, this option is incorrect.
- Therefore, "All of these" is **not the correct answer**.

6. **Conclusion**: After evaluating all the options, the only effective agent against viruses among the given options is **Interferons**.

### Final Answer:
The correct answer is **B) Interferons**.

---