During expiration, diaphragm becomes

Options

A. Flattened
B. Dome-shaped
C. Oblique
D. Normal

Answer

**Step-by-Step Solution:**

1. **Understanding the Diaphragm's Role**: The diaphragm is a major muscle involved in the process of respiration. It separates the thoracic cavity from the abdominal cavity and plays a crucial role in breathing.

2. **Inspiration Process**: During inhalation (inspiration), the diaphragm contracts. This contraction causes the diaphragm to flatten, which increases the volume of the thoracic cavity and allows air to flow into the lungs.

3. **Expiration Process**: During exhalation (expiration), the diaphragm relaxes. When the diaphragm relaxes, it returns to its original shape, which is dome-shaped. This dome shape decreases the volume of the thoracic cavity, pushing air out of the lungs.

4. **Conclusion**: Therefore, during expiration, the diaphragm becomes dome-shaped.

5. **Final Answer**: The correct option is 2: dome-shaped.

---