Function of allantois in mammal is

Options

A. Respiration only
B. Excretion
C. Nutrition, excretion and respiration
D. Protection from shocks

Explanation

### Step-by-Step Solution:

1. **Definition of Allantois**: The allantois is a membranous sac that is part of the developing embryo in mammals. It plays a crucial role in various physiological processes.

2. **Functions of Allantois**:
- **Nutrition**: The allantois serves as a site for nutrient exchange. It helps in the transport of nutrients from the mother to the developing embryo.
- **Respiration**: The allantois is involved in gas exchange. It facilitates the transfer of oxygen to the embryo and the removal of carbon dioxide.
- **Excretion**: The allantois collects waste products produced by the embryo. It helps in the excretion of these waste materials, preventing toxicity within the developing embryo.

3. **Conclusion**: Therefore, the allantois in mammals is primarily responsible for three key functions: nutrition, respiration, and excretion.

4. **Correct Option**: Based on the functions discussed, the correct answer to the question is Option C: Nutrition, excretion, and respiration.