If a person is infected with some deadly microbes to which quick immune response is required as in tetanus, the doctor needs to directly inject

Options

A. Antigenic protein of pathogen
B. Inactivated/weakned pathogens
C. Killed pathogens
D. Preformed antibodies/antitoxin

Answer

### Step-by-Step Solution:

1. **Understanding the Requirement**: The question states that a person is infected with deadly microbes and requires a quick immune response, similar to what is needed in cases like tetanus.

2. **Identifying the Need for Quick Response**: In cases of severe infections, the body needs an immediate defense mechanism to combat the pathogens. This is crucial when dealing with rapidly progressing diseases.

3. **Evaluating the Options**:
- **Antigenic protein of pathogen**: This would require time for the body to recognize and produce antibodies against the pathogen.
- **Inactivated pathogens**: Similar to antigenic proteins, these would also take time for the immune system to respond.
- **Killed pathogens**: Again, this option would not provide an immediate response as the body needs time to develop immunity.

4. **Choosing the Correct Option**: The only option that provides an immediate response is the injection of **preformed antibodies** or **antitoxins**. These are ready-made antibodies that can act quickly to neutralize the pathogens.

5. **Conclusion**: Therefore, in cases requiring a quick immune response, the doctor needs to directly inject **preformed antibodies or antitoxins**.

### Final Answer:
The doctor needs to directly inject **preformed antibodies or antitoxins**.

---