One of the followings is a very unique feature of the mammalian body

Options

A. Presence of diaphragm
B. Four-chambered heart
C. Rib cage
D. Homeothermy

Answer

To determine the unique feature of the mammalian body from the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify a feature that is exclusive to mammals, meaning it is not found in any other class of animals.

2. **Analyze Each Option**:
- **Presence of Diaphragm**: The diaphragm is a dome-shaped muscular membrane that separates the chest cavity from the abdominal cavity. This structure is unique to mammals.
- **Four Chambered Heart**: While mammals have a four-chambered heart, this feature is also present in birds (avians), making it not exclusive to mammals.
- **Rib Cage**: The rib cage is found in both mammals and reptiles, so it is not unique to mammals.
- **Homeothermia**: Warm-bloodedness (homeothermia) is a characteristic of mammals, but it is also seen in birds and some other animals, so it is not exclusive to mammals.

3. **Identify the Unique Feature**: Among the options analyzed, the presence of the diaphragm is the only feature that is exclusive to mammals.

4. **Conclusion**: The unique feature of the mammalian body is the presence of the diaphragm.

### Final Answer:
The unique feature of the mammalian body is the **presence of the diaphragm**.

---