Short-lived immunity acquired from mother to foetus across placenta or through mother's milk to the infant is catego- rized as:

Options

A. Active immunity
B. Passive immunity
C. Cellular immunity
D. Innate non-specific immunity

Answer

To solve the question regarding the type of immunity acquired from mother to fetus across the placenta or through mother's milk to the infant, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Types of Immunity**:
- Immunity can be categorized into several types: active immunity, passive immunity, cellular immunity, and innate non-specific immunity.

2. **Defining Passive Immunity**:
- Passive immunity refers to the transfer of ready-made antibodies from one individual to another. This type of immunity does not require the recipient's immune system to produce its own antibodies.

3. **Natural Transfer of Antibodies**:
- In the context of maternal immunity, passive immunity occurs naturally when maternal antibodies are transferred to the fetus through the placenta during pregnancy.

4. **Transfer Through Breast Milk**:
- Additionally, passive immunity is also conferred to the infant through breastfeeding, where antibodies present in the mother’s milk (especially colostrum) are passed to the infant.

5. **Duration of Passive Immunity**:
- It is important to note that this type of immunity is short-lived, as the antibodies received from the mother will eventually degrade and the infant's immune system will need to develop its own immunity.

6. **Conclusion**:
- Given the definitions and explanations, the type of immunity acquired from mother to fetus across the placenta or through mother's milk to the infant is categorized as **passive immunity**.

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