Which organ is not helpful in respiration in mammals?

Options

A. Ribs
B. Abdominal muscles
C. Diaphragm
D. Larynx

Explanation

To determine which organ is not helpful in respiration in mammals, we can analyze the options provided and their roles in the respiratory system.

### Step-by-Step Solution:

1. **Identify the Options**: The question likely presents several organs or structures, such as ribs, abdominal muscles, and the diaphragm.

2. **Analyze the Role of Each Organ**:
- **Ribs**: The ribs form a bony framework that protects the thoracic cavity and the lungs. They provide structural support and help in the mechanics of breathing by expanding and contracting during respiration, but they do not participate directly in the gas exchange process.
- **Abdominal Muscles**: These muscles support the trunk and help in maintaining internal pressure. They assist in forced expiration (like during heavy breathing) but are not directly involved in the respiration process itself.
- **Diaphragm**: The diaphragm is a crucial muscle in the respiratory system. It contracts to allow inhalation and relaxes to permit exhalation, directly facilitating the breathing process.

3. **Determine the Organ Not Helpful in Respiration**:
- Among the options, the **ribs** and **abdominal muscles** provide structural support and assist in the mechanics of breathing but do not directly participate in the gas exchange process. However, the ribs are primarily structural and do not aid in the actual breathing process as the diaphragm does.

4. **Conclusion**: Based on the analysis, the organ that is not helpful in respiration in mammals is the **ribs**.

### Final Answer:
The organ that is not helpful in respiration in mammals is the **ribs**.