Passive immunity can be conferred directly by

Options

A. vaccines
B. antitoxins
C. colostrum
D. both (b) and (c )

Explanation

To answer the question "Passive immunity can be conferred directly by," we will analyze the options provided: vaccines, antitoxins, cholesterol, and both B and C.

### Step-by-Step Solution:

1. **Understanding Passive Immunity**:
- Passive immunity refers to the transfer of antibodies from one individual to another. This can occur naturally (e.g., from mother to child) or artificially (e.g., through medical treatments).

2. **Evaluating the Options**:
- **Vaccines**:
- Vaccines work by introducing a weakened or killed form of a pathogen to stimulate the immune system to produce its own antibodies. This process is known as active immunity, not passive immunity. Therefore, this option is incorrect.

- **Antitoxins**:
- Antitoxins are preparations that contain antibodies against specific toxins. For example, tetanus antitoxin provides immediate immunity by supplying pre-formed antibodies. This is a clear example of passive immunity. Thus, this option is correct.

- **Cholesterol**:
- Cholesterol, specifically colostrum, is the first milk produced by mammals after giving birth. It is rich in antibodies and provides passive immunity to the newborn. Therefore, this option is also correct.

3. **Conclusion**:
- Since both antitoxins and cholesterol confer passive immunity, the correct answer is "both B and C." Thus, the answer is option D.

### Final Answer:
Passive immunity can be conferred directly by both antitoxins and cholesterol (option D).