Select the option that correctly describes ECG phase

Options

A. P - wave - Depolarisation of the ventricles
B. P - wave - Depolarisation of the A node
C. QRS wave - Depolarisation of the ventricles
D. T - wave - Depolarisation of the atria

Answer

To solve the question regarding the phases of the ECG (electrocardiogram), we need to analyze the components of the ECG wave and their corresponding physiological events in the heart.

### Step-by-Step Solution:

1. **Understanding ECG Components**:
- The ECG consists of several waves: P wave, QRS complex, and T wave. Each of these waves corresponds to specific electrical activities in the heart.

2. **Identifying the P Wave**:
- The P wave represents the depolarization of the atria. This is when the atria contract to push blood into the ventricles.
- The statement "P wave depolarization of the ventricles" is incorrect.

3. **Identifying the QRS Complex**:
- The QRS complex indicates the depolarization of the ventricles. This is when the ventricles contract to pump blood to the lungs and the rest of the body.
- The statement "QRS wave depolarization of the ventricles" is correct.

4. **Identifying the T Wave**:
- The T wave represents the repolarization of the ventricles. This is when the ventricles recover from contraction and prepare for the next heartbeat.
- The statement "T wave depolarization of the atria" is incorrect.

5. **Conclusion**:
- Based on the analysis, the correct option that describes the ECG phase is the one that states "QRS wave depolarization of the ventricles".

### Final Answer:
The correct option is: **QRS wave depolarization of the ventricles**.

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