Breathing, an important step of the respiratory system, is a two-part process involving-inhalation and exhalation. During the process of breathing, the thorax region shows some changes. Identify the statement/s from below that is/are related to the exhalation process.
I. External intercostal muscles contract
II. Pressure in the lungs increases
III. Diaphragm contracts
IV. The volume of thorax decreases

Options

A. II and IV only
B. I, II and III only
C. I , II , III and IV
D. II and III only

Answer

To solve the question regarding the statements related to the exhalation process in breathing, we will analyze each statement one by one:

1. **External intercostal muscles contract**: This statement is **incorrect**. The external intercostal muscles are responsible for inhalation. During inhalation, these muscles contract to expand the thoracic cavity. Therefore, this statement does not relate to exhalation.

2. **Pressure in the lungs increases**: This statement is **correct**. During exhalation, the diaphragm relaxes and the thoracic cavity volume decreases, which leads to an increase in pressure within the lungs. This pressure forces air out of the lungs.

3. **Diaphragm contracts**: This statement is **incorrect**. The diaphragm contracts during inhalation to allow the lungs to expand and fill with air. During exhalation, the diaphragm relaxes.

4. **The volume of thorax decreases**: This statement is **correct**. During exhalation, the diaphragm and intercostal muscles relax, which decreases the volume of the thoracic cavity. This decrease in volume contributes to the increase in lung pressure and facilitates the expulsion of air.

Based on this analysis, the statements related to the exhalation process are:

- **II. Pressure in the lungs increases**
- **IV. The volume of thorax decreases**

Thus, the correct answer is that statements II and IV are related to the exhalation process.

### Summary of the Solution:
- **Correct Statements**: II and IV
- **Incorrect Statements**: I and III